Introduce FormFieldChildElement and make FormField immutable

smack-core/src/main/java/org/jivesoftware/smack/util/CollectionUtil.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2015-2018 Florian Schmaus
+ * Copyright 2015-2019 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -49,4 +49,10 @@ public class CollectionUtil {
     public interface Predicate<T> {
         boolean test(T t);
     }
+
+    public static <T> ArrayList<T> newListWith(Collection<? extends T> collection) {
+        ArrayList<T> arrayList = new ArrayList<>(collection.size());
+        arrayList.addAll(collection);
+        return arrayList;
+    }
 }

smack-core/src/main/java/org/jivesoftware/smack/util/MultiMap.java

@@ -22,6 +22,7 @@ import java.util.LinkedHashMap;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Map.Entry;
 import java.util.Set;
 
 /**
@@ -57,7 +58,11 @@ public class MultiMap<K, V> {
      * @param size the initial capacity.
      */
     public MultiMap(int size) {
-        map = new LinkedHashMap<>(size);
+        this(new LinkedHashMap<>(size));
+    }
+
+    private MultiMap(Map<K, List<V>> map) {
+        this.map = map;
     }
 
     public int size() {
@@ -235,6 +240,18 @@ public class MultiMap<K, V> {
         return entrySet;
     }
 
+    public MultiMap<K, V> asUnmodifiableMultiMap() {
+        LinkedHashMap<K, List<V>> mapCopy = new LinkedHashMap<>(map.size());
+        for (Entry<K, List<V>> entry : map.entrySet()) {
+            K key = entry.getKey();
+            List<V> values = entry.getValue();
+
+            mapCopy.put(key, Collections.unmodifiableList(values));
+        }
+
+        return new MultiMap<K, V>(Collections.unmodifiableMap(mapCopy));
+    }
+
     private static final class SimpleMapEntry<K, V> implements Map.Entry<K, V> {
 
         private final K key;

smack-core/src/main/java/org/jivesoftware/smack/util/XmlStringBuilder.java

@@ -273,6 +273,15 @@ public class XmlStringBuilder implements Appendable, CharSequence, Element {
         return this;
     }
 
+    public <E extends Enum<?>> XmlStringBuilder attribute(String name, E value, E implicitDefault) {
+        if (value == null || value == implicitDefault) {
+            return this;
+        }
+
+        attribute(name, value.toString());
+        return this;
+    }
+
     public XmlStringBuilder attribute(String name, int value) {
         assert name != null;
         return attribute(name, String.valueOf(value));

smack-core/src/test/java/org/jivesoftware/smack/test/util/SmackTestSuite.java

@@ -18,6 +18,7 @@ package org.jivesoftware.smack.test.util;
 
 import java.util.Base64;
 
+import org.jivesoftware.smack.SmackConfiguration;
 import org.jivesoftware.smack.util.stringencoder.Base64.Encoder;
 
 /**
@@ -27,6 +28,7 @@ import org.jivesoftware.smack.util.stringencoder.Base64.Encoder;
 public class SmackTestSuite {
 
     static {
+        SmackConfiguration.getVersion();
         org.jivesoftware.smack.util.stringencoder.Base64.setEncoder(new Encoder() {
 
             @Override

smack-experimental/src/main/java/org/jivesoftware/smackx/mam/MamManager.java

@@ -21,6 +21,7 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Date;
 import java.util.HashMap;
+import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.WeakHashMap;
@@ -295,7 +296,7 @@ public final class MamManager extends Manager {
         public static final class Builder {
             private String node;
 
-            private final Map<String, FormField> formFields = new HashMap<>(8);
+            private final Map<String, FormField> formFields = new LinkedHashMap<>(8);
 
             private int maxResults = -1;
 
@@ -329,8 +330,9 @@ public final class MamManager extends Manager {
                     return this;
                 }
 
-                FormField formField = new FormField(FORM_FIELD_START);
+                FormField formField = FormField.builder(FORM_FIELD_START)
-                formField.addValue(start);
+                                .addValue(start)
+                                .build();
                 formFields.put(formField.getVariable(), formField);
 
                 FormField endFormField = formFields.get(FORM_FIELD_END);
@@ -356,8 +358,9 @@ public final class MamManager extends Manager {
                     return this;
                 }
 
-                FormField formField = new FormField(FORM_FIELD_END);
+                FormField formField = FormField.builder(FORM_FIELD_END)
-                formField.addValue(end);
+                    .addValue(end)
+                    .build();
                 formFields.put(formField.getVariable(), formField);
 
                 FormField startFormField = formFields.get(FORM_FIELD_START);
@@ -469,9 +472,9 @@ public final class MamManager extends Manager {
     }
 
     private static FormField getWithFormField(Jid withJid) {
-        FormField formField = new FormField(FORM_FIELD_WITH);
+        return FormField.builder(FORM_FIELD_WITH)
-        formField.addValue(withJid.toString());
+                        .addValue(withJid.toString())
-        return formField;
+                        .build();
     }
 
     public MamQuery queryMostRecentPage(Jid jid, int max) throws NoResponseException, XMPPErrorException,
@@ -711,9 +714,7 @@ public final class MamManager extends Manager {
     }
 
     private static DataForm getNewMamForm() {
-        FormField field = new FormField(FormField.FORM_TYPE);
+        FormField field = FormField.hiddenFormType(MamElements.NAMESPACE);
-        field.setType(FormField.Type.hidden);
-        field.addValue(MamElements.NAMESPACE);
         DataForm form = new DataForm(DataForm.Type.submit);
         form.addField(field);
         return form;

smack-experimental/src/main/java/org/jivesoftware/smackx/push_notifications/element/EnablePushNotificationsIQ.java

@@ -100,16 +100,19 @@ public class EnablePushNotificationsIQ extends IQ {
         if (publishOptions != null) {
             DataForm dataForm = new DataForm(DataForm.Type.submit);
 
-            FormField formTypeField = new FormField("FORM_TYPE");
+            // TODO: Shouldn't this use some potentially existing PubSub API? Also FORM_TYPE fields are usually of type
+            // 'hidden', but the examples in XEP-0357 do also not set the value to hidden and FORM_TYPE itself appears
+            // to be more convention than specification.
+            FormField.Builder formTypeField = FormField.builder("FORM_TYPE");
             formTypeField.addValue(PubSub.NAMESPACE + "#publish-options");
-            dataForm.addField(formTypeField);
+            dataForm.addField(formTypeField.build());
 
             Iterator<Map.Entry<String, String>> publishOptionsIterator = publishOptions.entrySet().iterator();
             while (publishOptionsIterator.hasNext()) {
                 Map.Entry<String, String> pairVariableValue = publishOptionsIterator.next();
-                FormField field = new FormField(pairVariableValue.getKey());
+                FormField.Builder field = FormField.builder(pairVariableValue.getKey());
                 field.addValue(pairVariableValue.getValue());
-                dataForm.addField(field);
+                dataForm.addField(field.build());
             }
 
             xml.element(dataForm);

smack-experimental/src/test/java/org/jivesoftware/smackx/mam/RetrieveFormFieldsTest.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2016 Fernando Ramirez, 2018 Florian Schmaus
+ * Copyright 2016 Fernando Ramirez, 2018-2019 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -36,7 +36,7 @@ public class RetrieveFormFieldsTest extends MamTest {
 
     private static final String additionalFieldsStanza = "<x xmlns='jabber:x:data' type='submit'>" + "<field var='FORM_TYPE' type='hidden'>"
             + "<value>" + MamElements.NAMESPACE + "</value>" + "</field>"
-            + "<field var='urn:example:xmpp:free-text-search' type='text-single'>" + "<value>Hi</value>" + "</field>"
+            + "<field var='urn:example:xmpp:free-text-search'>" + "<value>Hi</value>" + "</field>"
             + "<field var='urn:example:xmpp:stanza-content' type='jid-single'>" + "<value>Hi2</value>" + "</field>"
             + "</x>";
 
@@ -50,13 +50,15 @@ public class RetrieveFormFieldsTest extends MamTest {
 
     @Test
     public void checkAddAdditionalFieldsStanza() throws Exception {
-        FormField field1 = new FormField("urn:example:xmpp:free-text-search");
+        FormField field1 = FormField.builder("urn:example:xmpp:free-text-search")
-        field1.setType(FormField.Type.text_single);
+                        .setType(FormField.Type.text_single)
-        field1.addValue("Hi");
+                        .addValue("Hi")
+                        .build();
 
-        FormField field2 = new FormField("urn:example:xmpp:stanza-content");
+        FormField field2 = FormField.builder("urn:example:xmpp:stanza-content")
-        field2.setType(FormField.Type.jid_single);
+                        .setType(FormField.Type.jid_single)
-        field2.addValue("Hi2");
+                        .addValue("Hi2")
+                        .build();
 
         MamQueryArgs mamQueryArgs = MamQueryArgs.builder()
                         .withAdditionalFormField(field1)

smack-extensions/src/main/java/org/jivesoftware/smackx/admin/ServiceAdministrationManager.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2016 Florian Schmaus
+ * Copyright 2016-2019 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -30,11 +30,9 @@ import org.jivesoftware.smack.XMPPException.XMPPErrorException;
 import org.jivesoftware.smackx.commands.AdHocCommandManager;
 import org.jivesoftware.smackx.commands.RemoteCommand;
 import org.jivesoftware.smackx.xdata.Form;
-import org.jivesoftware.smackx.xdata.FormField;
 
 import org.jxmpp.jid.EntityBareJid;
 import org.jxmpp.jid.Jid;
-import org.jxmpp.jid.util.JidUtil;
 
 public class ServiceAdministrationManager extends Manager {
 
@@ -76,14 +74,9 @@ public class ServiceAdministrationManager extends Manager {
 
         Form answerForm = command.getForm().createAnswerForm();
 
-        FormField accountJidField = answerForm.getField("accountjid");
+        answerForm.setAnswer("accountjid", userJid);
-        accountJidField.addValue(userJid.toString());
+        answerForm.setAnswer("password", password);
-
+        answerForm.setAnswer("password-verify", password);
-        FormField passwordField = answerForm.getField("password");
-        passwordField.addValue(password);
-
-        FormField passwordVerifyField = answerForm.getField("password-verify");
-        passwordVerifyField.addValue(password);
 
         command.execute(answerForm);
         assert (command.isCompleted());
@@ -110,8 +103,7 @@ public class ServiceAdministrationManager extends Manager {
 
         Form answerForm = command.getForm().createAnswerForm();
 
-        FormField accountJids = answerForm.getField("accountjids");
+        answerForm.setAnswer("accountjids", jidsToDelete);
-        accountJids.addValues(JidUtil.toStringList(jidsToDelete));
 
         command.execute(answerForm);
         assert (command.isCompleted());

smack-extensions/src/main/java/org/jivesoftware/smackx/filetransfer/FileTransferNegotiator.java

@@ -226,7 +226,7 @@ public final class FileTransferNegotiator extends Manager {
         boolean isByteStream = false;
         boolean isIBB = false;
         for (FormField.Option option : field.getOptions()) {
-            variable = option.getValue();
+            variable = option.getValueString();
             if (variable.equals(Bytestream.NAMESPACE) && !IBB_ONLY) {
                 isByteStream = true;
             }
@@ -369,13 +369,15 @@ public final class FileTransferNegotiator extends Manager {
 
     private static DataForm createDefaultInitiationForm() {
         DataForm form = new DataForm(DataForm.Type.form);
-        FormField field = new FormField(STREAM_DATA_FIELD_NAME);
+        FormField.Builder fieldBuilder = FormField.builder();
-        field.setType(FormField.Type.list_single);
+        fieldBuilder.setFieldName(STREAM_DATA_FIELD_NAME)
+        .setType(FormField.Type.list_single);
+
         if (!IBB_ONLY) {
-            field.addOption(new FormField.Option(Bytestream.NAMESPACE));
+            fieldBuilder.addOption(Bytestream.NAMESPACE);
         }
-        field.addOption(new FormField.Option(DataPacketExtension.NAMESPACE));
+        fieldBuilder.addOption(DataPacketExtension.NAMESPACE);
-        form.addField(field);
+        form.addField(fieldBuilder.build());
         return form;
     }
 }

smack-extensions/src/main/java/org/jivesoftware/smackx/filetransfer/StreamNegotiator.java

@@ -81,12 +81,12 @@ public abstract class StreamNegotiator extends Manager {
         response.setStanzaId(streamInitiationOffer.getStanzaId());
 
         DataForm form = new DataForm(DataForm.Type.submit);
-        FormField field = new FormField(
+        FormField.Builder field = FormField.builder(
                 FileTransferNegotiator.STREAM_DATA_FIELD_NAME);
         for (String namespace : namespaces) {
             field.addValue(namespace);
         }
-        form.addField(field);
+        form.addField(field.build());
 
         response.setFeatureNegotiationForm(form);
         return response;

smack-extensions/src/main/java/org/jivesoftware/smackx/muc/MultiUserChat.java

@@ -1212,14 +1212,14 @@ public class MultiUserChat {
      */
     public void requestVoice() throws NotConnectedException, InterruptedException {
         DataForm form = new DataForm(DataForm.Type.submit);
-        FormField formTypeField = new FormField(FormField.FORM_TYPE);
+        FormField.Builder formTypeField = FormField.builder(FormField.FORM_TYPE);
         formTypeField.addValue(MUCInitialPresence.NAMESPACE + "#request");
-        form.addField(formTypeField);
+        form.addField(formTypeField.build());
-        FormField requestVoiceField = new FormField("muc#role");
+        FormField.Builder requestVoiceField = FormField.builder("muc#role");
         requestVoiceField.setType(FormField.Type.text_single);
         requestVoiceField.setLabel("Requested role");
         requestVoiceField.addValue("participant");
-        form.addField(requestVoiceField);
+        form.addField(requestVoiceField.build());
         Message message = new Message(room);
         message.addExtension(form);
         connection.sendStanza(message);

smack-extensions/src/main/java/org/jivesoftware/smackx/pubsub/ConfigureForm.java

@@ -665,8 +665,10 @@ public class ConfigureForm extends Form {
         String fieldName = nodeField.getFieldName();
 
         if (getField(fieldName) == null) {
-            FormField field = new FormField(fieldName);
+            FormField field = FormField.builder()
-            field.setType(type);
+                            .setVariable(fieldName)
+                            .setType(type)
+                            .build();
             addField(field);
         }
     }

smack-extensions/src/main/java/org/jivesoftware/smackx/pubsub/SubscribeForm.java

@@ -209,9 +209,9 @@ public class SubscribeForm extends Form {
         String fieldName = nodeField.getFieldName();
 
         if (getField(fieldName) == null) {
-            FormField field = new FormField(fieldName);
+            FormField.Builder field = FormField.builder(fieldName);
             field.setType(type);
-            addField(field);
+            addField(field.build());
         }
     }
 }

smack-extensions/src/main/java/org/jivesoftware/smackx/search/UserSearch.java

@@ -175,7 +175,7 @@ public class UserSearch extends SimpleIQ {
 
             if (eventType == XmlPullParser.Event.START_ELEMENT && !parser.getNamespace().equals("jabber:x:data")) {
                 String name = parser.getName();
-                FormField field = new FormField(name);
+                FormField.Builder field = FormField.builder(name);
 
                 // Handle hard coded values.
                 if (name.equals("first")) {
@@ -192,7 +192,7 @@ public class UserSearch extends SimpleIQ {
                 }
 
                 field.setType(FormField.Type.text_single);
-                dataForm.addField(field);
+                dataForm.addField(field.build());
             }
             else if (eventType == XmlPullParser.Event.END_ELEMENT) {
                 if (parser.getName().equals("query")) {

smack-extensions/src/main/java/org/jivesoftware/smackx/xdata/Form.java

@@ -17,6 +17,7 @@
 package org.jivesoftware.smackx.xdata;
 
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.Iterator;
 import java.util.List;
 import java.util.StringTokenizer;
@@ -107,7 +108,7 @@ public class Form {
      * @throws IllegalArgumentException if the form does not include the specified variable or
      *      if the answer type does not correspond with the field type..
      */
-    public void setAnswer(String variable, String value) {
+    public void setAnswer(String variable, CharSequence value) {
         FormField field = getField(variable);
         if (field == null) {
             throw new IllegalArgumentException("Field not found for the specified variable name.");
@@ -260,8 +261,9 @@ public class Form {
             throw new IllegalStateException("Cannot set an answer if the form is not of type " +
             "\"submit\"");
         }
-        field.resetValues();
+
-        field.addValue(value.toString());
+        FormField filledOutfield = field.buildAnswer().addValue(value.toString()).build();
+        dataForm.replaceField(filledOutfield);
     }
 
     /**
@@ -277,7 +279,7 @@ public class Form {
      * @throws IllegalStateException if the form is not of type "submit".
      * @throws IllegalArgumentException if the form does not include the specified variable.
      */
-    public void setAnswer(String variable, List<? extends CharSequence> values) {
+    public void setAnswer(String variable, Collection<? extends CharSequence> values) {
         if (!isSubmitType()) {
             throw new IllegalStateException("Cannot set an answer if the form is not of type " +
             "\"submit\"");
@@ -295,10 +297,9 @@ public class Form {
             default:
                 throw new IllegalArgumentException("This field only accept list of values.");
             }
-            // Clear the old values
+
-            field.resetValues();
+            FormField filledOutfield = field.buildAnswer().addValues(values).build();
-            // Set the new values. The string representation of each value will be actually used.
+            dataForm.replaceField(filledOutfield);
-            field.addValues(values);
         }
         else {
             throw new IllegalArgumentException("Couldn't find a field for the specified variable.");
@@ -321,12 +322,12 @@ public class Form {
         }
         FormField field = getField(variable);
         if (field != null) {
-            // Clear the old values
+            FormField.Builder filledOutFormFieldBuilder = field.buildAnswer();
-            field.resetValues();
             // Set the default value
             for (CharSequence value : field.getValues()) {
-                field.addValue(value);
+                filledOutFormFieldBuilder.addValue(value);
             }
+            dataForm.replaceField(filledOutFormFieldBuilder.build());
         }
         else {
             throw new IllegalArgumentException("Couldn't find a field for the specified variable.");
@@ -497,9 +498,9 @@ public class Form {
             // Add to the new form any type of field that includes a variable.
             // Note: The fields of type FIXED are the only ones that don't specify a variable
             if (field.getVariable() != null) {
-                FormField newField = new FormField(field.getVariable());
+                FormField.Builder newField = FormField.builder(field.getVariable());
                 newField.setType(field.getType());
-                form.addField(newField);
+                form.addField(newField.build());
                 // Set the answer ONLY to the hidden fields
                 if (field.getType() == FormField.Type.hidden) {
                     // Since a hidden field could have many values we need to collect them

smack-extensions/src/main/java/org/jivesoftware/smackx/xdata/FormField.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2003-2007 Jive Software.
+ * Copyright 2003-2007 Jive Software, 2019 Florian Schmaus.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,16 +19,21 @@ package org.jivesoftware.smackx.xdata;
 
 import java.text.ParseException;
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.Date;
+import java.util.Iterator;
 import java.util.List;
 
-import org.jivesoftware.smack.packet.NamedElement;
+import javax.xml.namespace.QName;
+
+import org.jivesoftware.smack.packet.FullyQualifiedElement;
 import org.jivesoftware.smack.packet.XmlEnvironment;
-import org.jivesoftware.smack.util.StringUtils;
+import org.jivesoftware.smack.util.CollectionUtil;
+import org.jivesoftware.smack.util.MultiMap;
 import org.jivesoftware.smack.util.XmlStringBuilder;
 
-import org.jivesoftware.smackx.xdatavalidation.packet.ValidateElement;
+import org.jivesoftware.smackx.xdata.packet.DataForm;
 
 import org.jxmpp.util.XmppDateTime;
 
@@ -39,10 +44,14 @@ import org.jxmpp.util.XmppDateTime;
  *
  * @author Gaston Dombiak
  */
-public class FormField implements NamedElement {
+public final class FormField implements FullyQualifiedElement {
 
     public static final String ELEMENT = "field";
 
+    public static final String NAMESPACE = DataForm.NAMESPACE;
+
+    public static final QName QNAME = new QName(NAMESPACE, ELEMENT);
+
     /**
      * The constant String "FORM_TYPE".
      */
@@ -140,33 +149,91 @@ public class FormField implements NamedElement {
         }
     }
 
+    /**
+     * The field's name. Put as value in the 'var' attribute of <field/>.
+     */
     private final String variable;
 
-    private String description;
+    private final String label;
-    private boolean required = false;
-    private String label;
-    private Type type;
-    private final List<Option> options = new ArrayList<>();
-    private final List<CharSequence> values = new ArrayList<>();
-    private ValidateElement validateElement;
 
-    /**
+    private final Type type;
-     * Creates a new FormField with the variable name that uniquely identifies the field
+
-     * in the context of the form.
+    private final List<FormFieldChildElement> formFieldChildElements;
-     *
+
-     * @param variable the variable name of the question.
+    private final MultiMap<QName, FormFieldChildElement> formFieldChildElementsMap;
+
+    /*
+     * The following four fields are cache values which are represented as child elements of </form> and hence also
+     * appear in formFieldChildElements.
      */
-    public FormField(String variable) {
+    private final List<Option> options;
-        this.variable = StringUtils.requireNotNullNorEmpty(variable, "Variable must not be null nor empty");
+    private final List<CharSequence> values;
+    private final String description;
+    private final boolean required;
+
+    private MultiMap<QName, FormFieldChildElement> createChildElementsMap() {
+        MultiMap<QName, FormFieldChildElement> formFieldChildElementsMap = new MultiMap<>(formFieldChildElements.size());
+        for (FormFieldChildElement formFieldChildElement : formFieldChildElements) {
+            formFieldChildElementsMap.put(formFieldChildElement.getQName(), formFieldChildElement);
+        }
+        return formFieldChildElementsMap.asUnmodifiableMultiMap();
     }
 
-    /**
+    private FormField(String value) {
-     * Creates a new FormField of type FIXED. The fields of type FIXED do not define a variable
+        variable = FORM_TYPE;
-     * name.
+        type = Type.hidden;
-     */
+        label = null;
-    public FormField() {
+        required = false;
-        this.variable = null;
+        description = null;
-        this.type = Type.fixed;
+
+        formFieldChildElements = Collections.singletonList(new Value(value));
+        values = Collections.singletonList(value);
+        options = Collections.emptyList();
+
+        formFieldChildElementsMap = createChildElementsMap();
+    }
+
+    private FormField(Builder builder) {
+        variable = builder.variable;
+        label = builder.label;
+        type = builder.type;
+        if (builder.formFieldChildElements != null) {
+            formFieldChildElements = Collections.unmodifiableList(builder.formFieldChildElements);
+        } else {
+            formFieldChildElements = Collections.emptyList();
+        }
+
+        if (variable == null && type != Type.fixed) {
+            throw new IllegalArgumentException("The variable can only be null if the form is of type fixed");
+        }
+
+        String description = null;
+        boolean requiredElementAsChild = false;
+        ArrayList<Option> options = new ArrayList<>(formFieldChildElements.size());
+        ArrayList<CharSequence> values = new ArrayList<>(formFieldChildElements.size());
+        for (FormFieldChildElement formFieldChildElement : formFieldChildElements) {
+            if (formFieldChildElement instanceof Value) {
+                Value value = (Value) formFieldChildElement;
+                values.add(value.getValue());
+            } else if (formFieldChildElement instanceof Option) {
+                Option option = (Option) formFieldChildElement;
+                options.add(option);
+            } else if (formFieldChildElement instanceof Description) {
+                description = ((Description) formFieldChildElement).getDescription();
+            // Required is a singleton instance.
+            } else if (formFieldChildElement == Required.INSTANCE) {
+                requiredElementAsChild = true;
+            }
+        }
+        options.trimToSize();
+        values.trimToSize();
+        this.options = Collections.unmodifiableList(options);
+        this.values = Collections.unmodifiableList(values);
+        this.description = description;
+
+        required = requiredElementAsChild;
+
+        formFieldChildElementsMap = createChildElementsMap();
     }
 
     /**
@@ -200,9 +267,7 @@ public class FormField implements NamedElement {
      * @return List of the available options.
      */
     public List<Option> getOptions() {
-        synchronized (options) {
+        return options;
-            return Collections.unmodifiableList(new ArrayList<>(options));
-        }
     }
 
     /**
@@ -221,6 +286,9 @@ public class FormField implements NamedElement {
      * @see Type
      */
     public Type getType() {
+        if (type == null) {
+            return Type.text_single;
+        }
         return type;
     }
 
@@ -289,143 +357,25 @@ public class FormField implements NamedElement {
     }
 
     /**
-     * Returns the variable name that the question is filling out.
+     * Returns the field's name, also known as the variable name in case this is an filled out answer form.
      * <p>
      * According to XEP-4 § 3.2 the variable name (the 'var' attribute)
      * "uniquely identifies the field in the context of the form" (if the field is not of type 'fixed', in which case
      * the field "MAY possess a 'var' attribute")
      * </p>
      *
-     * @return the variable name of the question.
+     * @return the field's name.
      */
     public String getVariable() {
         return variable;
     }
 
-    /**
+    public FormFieldChildElement getFormFieldChildElement(QName qname) {
-     * Get validate element.
+        return formFieldChildElementsMap.getFirst(qname);
-     *
-     * @return the validateElement
-     */
-    public ValidateElement getValidateElement() {
-        return validateElement;
     }
 
-    /**
+    public List<FormFieldChildElement> getFormFieldChildElements(QName qname) {
-     * Sets a description that provides extra clarification about the question. This information
+        return formFieldChildElementsMap.getAll(qname);
-     * could be presented to the user either in tool-tip, help button, or as a section of text
-     * before the question.
-     * <p>
-     * If the question is of type FIXED then the description should remain empty.
-     * </p>
-     *
-     * @param description provides extra clarification about the question.
-     */
-    public void setDescription(String description) {
-        this.description = description;
-    }
-
-    /**
-     * Sets the label of the question which should give enough information to the user to
-     * fill out the form.
-     *
-     * @param label the label of the question.
-     */
-    public void setLabel(String label) {
-        this.label = label;
-    }
-
-    /**
-     * Sets if the question must be answered in order to complete the questionnaire.
-     *
-     * @param required if the question must be answered in order to complete the questionnaire.
-     */
-    public void setRequired(boolean required) {
-        this.required = required;
-    }
-
-    /**
-     * Set validate element.
-     * @param validateElement the validateElement to set
-     */
-    public void setValidateElement(ValidateElement validateElement) {
-        validateElement.checkConsistency(this);
-        this.validateElement = validateElement;
-    }
-
-    /**
-     * Sets an indicative of the format for the data to answer.
-     * <p>
-     * This method will throw an IllegalArgumentException if type is 'fixed'. To create FormFields of type 'fixed' use
-     * {@link #FormField()} instead.
-     * </p>
-     *
-     * @param type an indicative of the format for the data to answer.
-     * @see Type
-     * @throws IllegalArgumentException if type is 'fixed'.
-     */
-    public void setType(Type type) {
-        if (type == Type.fixed) {
-            throw new IllegalArgumentException("Can not set type to fixed, use FormField constructor without arguments instead.");
-        }
-        this.type = type;
-    }
-
-    /**
-     * Adds a default value to the question if the question is part of a form to fill out.
-     * Otherwise, adds an answered value to the question.
-     *
-     * @param value a default value or an answered value of the question.
-     */
-    public void addValue(CharSequence value) {
-        synchronized (values) {
-            values.add(value);
-        }
-    }
-
-    /**
-     * Adds the given Date as XEP-0082 formated string by invoking {@link #addValue(CharSequence)} after the date
-     * instance was formated.
-     *
-     * @param date the date instance to add as XEP-0082 formated string.
-     * @since 4.3.0
-     */
-    public void addValue(Date date) {
-        String dateString = XmppDateTime.formatXEP0082Date(date);
-        addValue(dateString);
-    }
-
-    /**
-     * Adds a default values to the question if the question is part of a form to fill out.
-     * Otherwise, adds an answered values to the question.
-     *
-     * @param newValues default values or an answered values of the question.
-     */
-    public void addValues(List<? extends CharSequence> newValues) {
-        synchronized (values) {
-            values.addAll(newValues);
-        }
-    }
-
-    /**
-     * Removes all the values of the field.
-     */
-    protected void resetValues() {
-        synchronized (values) {
-            values.clear();
-        }
-    }
-
-    /**
-     * Adss an available options to the question that the user has in order to answer
-     * the question.
-     *
-     * @param option a new available option for the question.
-     */
-    public void addOption(Option option) {
-        synchronized (options) {
-            options.add(option);
-        }
     }
 
     @Override
@@ -433,27 +383,42 @@ public class FormField implements NamedElement {
         return ELEMENT;
     }
 
+    @Override
+    public String getNamespace() {
+        return NAMESPACE;
+    }
+
+    @Override
+    public QName getQName() {
+        return QNAME;
+    }
+
+    public Builder buildAnswer() {
+        return asBuilder().resetValues();
+    }
+
+    public Builder asBuilder() {
+        return new Builder(this);
+    }
+
     @Override
     public XmlStringBuilder toXML(XmlEnvironment enclosingNamespace) {
-        XmlStringBuilder buf = new XmlStringBuilder(this);
+        XmlStringBuilder buf = new XmlStringBuilder(this, enclosingNamespace);
         // Add attributes
         buf.optAttribute("label", getLabel());
         buf.optAttribute("var", getVariable());
-        buf.optAttribute("type", getType());
+        // If no 'type' is specified, the default is "text-single";
-        buf.rightAngleBracket();
+        buf.attribute("type", getType(), Type.text_single);
-        // Add elements
+
-        buf.optElement("desc", getDescription());
+        if (formFieldChildElements.isEmpty()) {
-        buf.condEmptyElement(isRequired(), "required");
+            buf.closeEmptyElement();
-        // Loop through all the values and append them to the string buffer
+        } else {
-        for (CharSequence value : getValues()) {
+            buf.rightAngleBracket();
-            buf.element("value", value);
+
+            buf.append(formFieldChildElements, enclosingNamespace);
+
+            buf.closeElement(this);
         }
-        // Loop through all the values and append them to the string buffer
-        for (Option option : getOptions()) {
-            buf.append(option.toXML());
-        }
-        buf.optElement(validateElement);
-        buf.closeElement(this);
         return buf;
     }
 
@@ -476,23 +441,268 @@ public class FormField implements NamedElement {
         return toXML().toString().hashCode();
     }
 
+    public static FormField hiddenFormType(String value) {
+        return new FormField(value);
+    }
+
+    public static Builder builder(String fieldName) {
+        return builder().setFieldName(fieldName);
+    }
+
+    public static Builder builder() {
+        return new Builder();
+    }
+
+    public static final class Builder {
+        private String variable;
+
+        private String label;
+
+        private Type type;
+
+        private List<FormFieldChildElement> formFieldChildElements;
+
+        private boolean disallowType;
+        private boolean disallowFurtherFormFieldChildElements;
+
+        private Builder() {
+        }
+
+        private Builder(FormField formField) {
+            variable = formField.variable;
+            label = formField.label;
+            type = formField.type;
+            // Create a new modifiable list.
+            formFieldChildElements = CollectionUtil.newListWith(formField.formFieldChildElements);
+        }
+
+        public Builder setFieldName(String fieldName) {
+            return setVariable(fieldName);
+        }
+
+        public Builder setVariable(String variable) {
+            this.variable = variable;
+            return this;
+        }
+
+        /**
+         * Sets an indicative of the format for the data to answer.
+         *
+         * @param type an indicative of the format for the data to answer.
+         * @see Type
+         */
+        public Builder setType(Type type) {
+            final Type oldType = this.type;
+
+            this.type = type;
+
+            try {
+                checkFormFieldChildElementsConsistency();
+            } catch (IllegalArgumentException e) {
+                this.type = oldType;
+                throw e;
+            }
+
+            return this;
+        }
+
+        /**
+         * Sets a description that provides extra clarification about the question. This information
+         * could be presented to the user either in tool-tip, help button, or as a section of text
+         * before the question.
+         * <p>
+         * If the question is of type FIXED then the description should remain empty.
+         * </p>
+         *
+         * @param description provides extra clarification about the question.
+         */
+        public Builder setDescription(String description) {
+            Description descriptionElement = new Description(description);
+            setOnlyElement(descriptionElement, Description.class);
+            return this;
+        }
+
+        /**
+         * Sets the label of the question which should give enough information to the user to
+         * fill out the form.
+         *
+         * @param label the label of the question.
+         */
+        public Builder setLabel(String label) {
+            this.label = label;
+            return this;
+        }
+
+        /**
+         * Sets if the question must be answered in order to complete the questionnaire.
+         *
+         * @param required if the question must be answered in order to complete the questionnaire.
+         */
+        public Builder setRequired(boolean required) {
+            setOnlyElement(Required.INSTANCE, Required.class);
+            return this;
+        }
+
+        /**
+         * Adds a default value to the question if the question is part of a form to fill out.
+         * Otherwise, adds an answered value to the question.
+         *
+         * @param value a default value or an answered value of the question.
+         */
+        public Builder addValue(CharSequence value) {
+            return addFormFieldChildElement(new Value(value));
+        }
+
+        /**
+         * Adds the given Date as XEP-0082 formated string by invoking {@link #addValue(CharSequence)} after the date
+         * instance was formated.
+         *
+         * @param date the date instance to add as XEP-0082 formated string.
+         */
+        public Builder addValue(Date date) {
+            String dateString = XmppDateTime.formatXEP0082Date(date);
+            return addValue(dateString);
+        }
+
+        /**
+         * Adds a default values to the question if the question is part of a form to fill out.
+         * Otherwise, adds an answered values to the question.
+         *
+         * @param values default values or an answered values of the question.
+         */
+        public Builder addValues(Collection<? extends CharSequence> values) {
+            for (CharSequence value : values) {
+                addValue(value);
+            }
+            return this;
+        }
+
+        public Builder addOption(String option) {
+            return addOption(new Option(option));
+        }
+
+        /**
+         * Adds an available options to the question that the user has in order to answer
+         * the question.
+         *
+         * @param option a new available option for the question.
+         */
+        public Builder addOption(Option option) {
+            return addFormFieldChildElement(option);
+        }
+
+        public Builder addFormFieldChildElement(FormFieldChildElement formFieldChildElement) {
+            if (disallowFurtherFormFieldChildElements) {
+                throw new IllegalArgumentException();
+            }
+
+            if (formFieldChildElement.requiresNoTypeSet() && type != null) {
+                throw new IllegalArgumentException("Elements of type " + formFieldChildElement.getClass()
+                                + " can only be added to form fields where no type is set");
+            }
+
+            ensureThatFormFieldChildElementsIsSet();
+
+            if (!formFieldChildElements.isEmpty() && formFieldChildElement.isExclusiveElement()) {
+                throw new IllegalArgumentException("Elements of type " + formFieldChildElement.getClass()
+                                + " must be the only child elements of a form field.");
+            }
+
+            disallowType = disallowType || formFieldChildElement.requiresNoTypeSet();
+            disallowFurtherFormFieldChildElements = formFieldChildElement.isExclusiveElement();
+
+            formFieldChildElements.add(formFieldChildElement);
+
+            return this;
+        }
+
+        public Builder resetValues() {
+            if (formFieldChildElements == null) {
+                return this;
+            }
+
+            // TODO: Use Java' stream API once Smack's minimum Android SDK level is 24 or higher.
+            Iterator<FormFieldChildElement> it = formFieldChildElements.iterator();
+            while (it.hasNext()) {
+                FormFieldChildElement formFieldChildElement = it.next();
+                if (formFieldChildElement instanceof Value) {
+                    it.remove();
+                }
+            }
+
+            disallowType = disallowFurtherFormFieldChildElements = false;
+
+            return this;
+        }
+
+        public FormField build() {
+            return new FormField(this);
+        }
+
+        public Type getType() {
+            return type;
+        }
+
+        private void ensureThatFormFieldChildElementsIsSet() {
+            if (formFieldChildElements == null) {
+                formFieldChildElements = new ArrayList<>(4);
+            }
+        }
+
+        private <E extends FormFieldChildElement> void setOnlyElement(E element, Class<E> elementClass) {
+            ensureThatFormFieldChildElementsIsSet();
+            for (int i = 0; i < formFieldChildElements.size(); i++) {
+                if (formFieldChildElements.get(i).getClass().equals(elementClass)) {
+                    formFieldChildElements.set(i, element);
+                    return;
+                }
+            }
+
+            formFieldChildElements.add(0, element);
+        }
+
+        private void checkFormFieldChildElementsConsistency() {
+            if (formFieldChildElements == null) {
+                return;
+            }
+
+            for (FormFieldChildElement formFiledChildElement : formFieldChildElements) {
+                formFiledChildElement.checkConsistency(this);
+            }
+        }
+    }
+
+    /**
+     * Marker class for the standard, as per XEP-0004, child elements of form fields.
+     */
+    private abstract static class StandardFormFieldChildElement implements FormFieldChildElement {
+    }
+
     /**
      * Represents the available option of a given FormField.
      *
      * @author Gaston Dombiak
      */
-    public static final class Option implements NamedElement {
+    public static final class Option extends StandardFormFieldChildElement {
 
         public static final String ELEMENT = "option";
 
-        private final String value;
+        public static final QName QNAME = new QName(NAMESPACE, ELEMENT);
-        private String label;
+
+        private final String label;
+
+        private final Value value;
 
         public Option(String value) {
-            this.value = value;
+            this(null, value);
         }
 
         public Option(String label, String value) {
+            this.label = label;
+            this.value = new Value(value);
+        }
+
+        public Option(String label, Value value) {
             this.label = label;
             this.value = value;
         }
@@ -511,10 +721,19 @@ public class FormField implements NamedElement {
          *
          * @return the value of the option.
          */
-        public String getValue() {
+        public Value getValue() {
             return value;
         }
 
+        /**
+         * Returns the string representation of the value of the option.
+         *
+         * @return the value of the option.
+         */
+        public String getValueString() {
+            return value.value.toString();
+        }
+
         @Override
         public String toString() {
             return getLabel();
@@ -525,6 +744,16 @@ public class FormField implements NamedElement {
             return ELEMENT;
         }
 
+        @Override
+        public String getNamespace() {
+            return NAMESPACE;
+        }
+
+        @Override
+        public QName getQName() {
+            return QNAME;
+        }
+
         @Override
         public XmlStringBuilder toXML(org.jivesoftware.smack.packet.XmlEnvironment enclosingNamespace) {
             XmlStringBuilder xml = new XmlStringBuilder(this);
@@ -533,7 +762,7 @@ public class FormField implements NamedElement {
             xml.rightAngleBracket();
 
             // Add element
-            xml.element("value", getValue());
+            xml.element("value", getValueString());
 
             xml.closeElement(this);
             return xml;
@@ -569,5 +798,124 @@ public class FormField implements NamedElement {
             result = 37 * result + (label == null ? 0 : label.hashCode());
             return result;
         }
+
+    }
+
+    public static class Description extends StandardFormFieldChildElement {
+
+        public static final String ELEMENT = "desc";
+
+        public static final QName QNAME = new QName(NAMESPACE, ELEMENT);
+
+        private final String description;
+
+        public Description(String description) {
+            this.description = description;
+        }
+
+        public String getDescription() {
+            return description;
+        }
+
+        @Override
+        public String getElementName() {
+            return ELEMENT;
+        }
+
+        @Override
+        public String getNamespace() {
+            return NAMESPACE;
+        }
+
+        @Override
+        public QName getQName() {
+            return QNAME;
+        }
+
+        @Override
+        public XmlStringBuilder toXML(XmlEnvironment xmlEnvironment) {
+            XmlStringBuilder xml = new XmlStringBuilder(this, xmlEnvironment);
+            xml.rightAngleBracket();
+            xml.escape(description);
+            xml.closeElement(this);
+            return xml;
+        }
+    }
+
+    public static final class Required extends StandardFormFieldChildElement {
+
+        public static final Required INSTANCE = new Required();
+
+        public static final String ELEMENT = "required";
+
+        public static final QName QNAME = new QName(NAMESPACE, ELEMENT);
+
+        private Required() {
+        }
+
+        @Override
+        public String getElementName() {
+            return ELEMENT;
+        }
+
+        @Override
+        public String getNamespace() {
+            return NAMESPACE;
+        }
+
+        @Override
+        public QName getQName() {
+            return QNAME;
+        }
+
+        @Override
+        public boolean mustBeOnlyOfHisKind() {
+            return true;
+        }
+
+        @Override
+        public String toXML(XmlEnvironment xmlEnvironment) {
+            return '<' + ELEMENT + "/>";
+        }
+    }
+
+    public static class Value extends StandardFormFieldChildElement {
+
+        public static final String ELEMENT = "value";
+
+        public static final QName QNAME = new QName(NAMESPACE, ELEMENT);
+
+        private final CharSequence value;
+
+        public Value(CharSequence value) {
+            this.value = value;
+        }
+
+        public CharSequence getValue() {
+            return value;
+        }
+
+        @Override
+        public String getElementName() {
+            return ELEMENT;
+        }
+
+        @Override
+        public String getNamespace() {
+            return NAMESPACE;
+        }
+
+        @Override
+        public QName getQName() {
+            return QNAME;
+        }
+
+        @Override
+        public XmlStringBuilder toXML(XmlEnvironment xmlEnvironment) {
+            XmlStringBuilder xml = new XmlStringBuilder(this, xmlEnvironment);
+            xml.rightAngleBracket();
+            xml.escape(value);
+            return xml.closeElement(this);
+        }
     }
 }

smack-extensions/src/main/java/org/jivesoftware/smackx/xdata/FormFieldChildElement.java

@@ -0,0 +1,39 @@
+/**
+ *
+ * Copyright 2019 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.xdata;
+
+import org.jivesoftware.smack.packet.FullyQualifiedElement;
+
+public interface FormFieldChildElement extends FullyQualifiedElement {
+
+    default boolean isExclusiveElement() {
+        return false;
+    }
+
+    default boolean requiresNoTypeSet() {
+        return isExclusiveElement();
+    }
+
+    default boolean mustBeOnlyOfHisKind() {
+        return false;
+    }
+
+    default void checkConsistency(FormField.Builder formFieldBuilder) throws IllegalArgumentException {
+        // Does nothing per default.
+    }
+
+}

smack-extensions/src/main/java/org/jivesoftware/smackx/xdata/XDataManager.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2014-2015 Florian Schmaus
+ * Copyright 2014-2019 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -29,6 +29,11 @@ import org.jivesoftware.smack.XMPPException.XMPPErrorException;
 
 import org.jivesoftware.smackx.disco.ServiceDiscoveryManager;
 import org.jivesoftware.smackx.xdata.packet.DataForm;
+import org.jivesoftware.smackx.xdata.provider.DescriptionProvider;
+import org.jivesoftware.smackx.xdata.provider.FormFieldChildElementProviderManager;
+import org.jivesoftware.smackx.xdata.provider.OptionProvider;
+import org.jivesoftware.smackx.xdata.provider.RequiredProvider;
+import org.jivesoftware.smackx.xdata.provider.ValueProvider;
 
 import org.jxmpp.jid.Jid;
 
@@ -40,6 +45,13 @@ public final class XDataManager extends Manager {
     public static final String NAMESPACE = DataForm.NAMESPACE;
 
     static {
+        FormFieldChildElementProviderManager.addFormFieldChildElementProvider(
+                        new DescriptionProvider(),
+                        new OptionProvider(),
+                        new RequiredProvider(),
+                        new ValueProvider()
+        );
+
         XMPPConnectionRegistry.addConnectionCreationListener(new ConnectionCreationListener() {
             @Override
             public void connectionCreated(XMPPConnection connection) {

smack-extensions/src/main/java/org/jivesoftware/smackx/xdata/packet/DataForm.java

@@ -28,6 +28,7 @@ import java.util.Map;
 import org.jivesoftware.smack.packet.Element;
 import org.jivesoftware.smack.packet.ExtensionElement;
 import org.jivesoftware.smack.packet.Stanza;
+import org.jivesoftware.smack.packet.XmlEnvironment;
 import org.jivesoftware.smack.util.XmlStringBuilder;
 
 import org.jivesoftware.smackx.xdata.FormField;
@@ -160,6 +161,17 @@ public class DataForm implements ExtensionElement {
         }
     }
 
+    public FormField replaceField(FormField field) {
+        String fieldVariableName = field.getVariable();
+
+        synchronized (fields) {
+            if (!fields.containsKey(fieldVariableName)) {
+                throw new IllegalArgumentException("No field with the name " + fieldVariableName + " exists");
+            }
+            return fields.put(fieldVariableName, field);
+        }
+    }
+
     /**
      * Check if a form field with the given variable name exists.
      *
@@ -312,11 +324,16 @@ public class DataForm implements ExtensionElement {
     }
 
     @Override
-    public XmlStringBuilder toXML(org.jivesoftware.smack.packet.XmlEnvironment enclosingNamespace) {
+    public XmlStringBuilder toXML(XmlEnvironment xmlEnvironment) {
         XmlStringBuilder buf = new XmlStringBuilder(this);
         buf.attribute("type", getType());
         buf.rightAngleBracket();
 
+        XmlEnvironment dataFormxmlEnvironment = XmlEnvironment.builder()
+                        .withNamespace(NAMESPACE)
+                        .withNext(xmlEnvironment)
+                        .build();
+
         buf.optElement("title", getTitle());
         for (String instruction : getInstructions()) {
             buf.element("instructions", instruction);
@@ -329,10 +346,8 @@ public class DataForm implements ExtensionElement {
         for (Item item : getItems()) {
             buf.append(item.toXML());
         }
-        // Loop through all the form fields and append them to the string buffer
+        // Add all form fields.
-        for (FormField field : getFields()) {
+        buf.append(getFields(), dataFormxmlEnvironment);
-            buf.append(field.toXML());
-        }
         for (Element element : extensionElements) {
             buf.append(element.toXML());
         }

smack-extensions/src/main/java/org/jivesoftware/smackx/xdata/provider/DataFormProvider.java

@@ -20,21 +20,24 @@ package org.jivesoftware.smackx.xdata.provider;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.logging.Logger;
+
+import javax.xml.namespace.QName;
 
 import org.jivesoftware.smack.packet.XmlEnvironment;
 import org.jivesoftware.smack.parsing.SmackParsingException;
 import org.jivesoftware.smack.provider.ExtensionElementProvider;
 import org.jivesoftware.smack.roster.packet.RosterPacket;
 import org.jivesoftware.smack.roster.provider.RosterPacketProvider;
+import org.jivesoftware.smack.util.StringUtils;
 import org.jivesoftware.smack.xml.XmlPullParser;
 import org.jivesoftware.smack.xml.XmlPullParserException;
 
 import org.jivesoftware.smackx.xdata.FormField;
+import org.jivesoftware.smackx.xdata.FormFieldChildElement;
 import org.jivesoftware.smackx.xdata.packet.DataForm;
 import org.jivesoftware.smackx.xdatalayout.packet.DataLayout;
 import org.jivesoftware.smackx.xdatalayout.provider.DataLayoutProvider;
-import org.jivesoftware.smackx.xdatavalidation.packet.ValidateElement;
-import org.jivesoftware.smackx.xdatavalidation.provider.DataValidationProvider;
 
 /**
  * The DataFormProvider parses DataForm packets.
@@ -43,6 +46,8 @@ import org.jivesoftware.smackx.xdatavalidation.provider.DataValidationProvider;
  */
 public class DataFormProvider extends ExtensionElementProvider<DataForm> {
 
+    private static final Logger LOGGER = Logger.getLogger(DataFormProvider.class.getName());
+
     public static final DataFormProvider INSTANCE = new DataFormProvider();
 
     @Override
@@ -55,6 +60,7 @@ public class DataFormProvider extends ExtensionElementProvider<DataForm> {
             case START_ELEMENT:
                 String name = parser.getName();
                 String namespace = parser.getNamespace();
+                XmlEnvironment elementXmlEnvironment = XmlEnvironment.from(parser, xmlEnvironment);
                 switch (name) {
                 case "instructions":
                     dataForm.addInstruction(parser.nextText());
@@ -63,13 +69,16 @@ public class DataFormProvider extends ExtensionElementProvider<DataForm> {
                     dataForm.setTitle(parser.nextText());
                     break;
                 case "field":
-                    dataForm.addField(parseField(parser));
+                    FormField formField = parseField(parser, elementXmlEnvironment);
+                    dataForm.addField(formField);
                     break;
                 case "item":
-                    dataForm.addItem(parseItem(parser));
+                    DataForm.Item item = parseItem(parser, elementXmlEnvironment);
+                    dataForm.addItem(item);
                     break;
                 case "reported":
-                    dataForm.setReportedData(parseReported(parser));
+                    DataForm.ReportedData reported = parseReported(parser, elementXmlEnvironment);
+                    dataForm.setReportedData(reported);
                     break;
                 // See XEP-133 Example 32 for a corner case where the data form contains this extension.
                 case RosterPacket.ELEMENT:
@@ -98,45 +107,35 @@ public class DataFormProvider extends ExtensionElementProvider<DataForm> {
         return dataForm;
     }
 
-    private static FormField parseField(XmlPullParser parser) throws XmlPullParserException, IOException {
+    private static FormField parseField(XmlPullParser parser, XmlEnvironment xmlEnvironment)
+                    throws XmlPullParserException, IOException, SmackParsingException {
         final int initialDepth = parser.getDepth();
+
         final String var = parser.getAttributeValue("", "var");
         final FormField.Type type = FormField.Type.fromString(parser.getAttributeValue("", "type"));
 
-        final FormField formField;
+        final FormField.Builder builder = FormField.builder();
-        if (type == FormField.Type.fixed) {
+        builder.setType(type);
-            formField = new FormField();
+        if (type != FormField.Type.fixed) {
-        } else {
+            builder.setVariable(var);
-            formField = new FormField(var);
+        }
-            formField.setType(type);
+        String label = parser.getAttributeValue("", "label");
+        if (StringUtils.isNotEmpty(label)) {
+            builder.setLabel(label);
         }
-        formField.setLabel(parser.getAttributeValue("", "label"));
 
         outerloop: while (true) {
             XmlPullParser.Event eventType = parser.next();
             switch (eventType) {
             case START_ELEMENT:
-                String name = parser.getName();
+                QName qname = parser.getQName();
-                String namespace = parser.getNamespace();
+                FormFieldChildElementProvider<?> provider = FormFieldChildElementProviderManager.getFormFieldChildElementProvider(
-                switch (name) {
+                                qname);
-                case "desc":
+                if (provider != null) {
-                    formField.setDescription(parser.nextText());
+                    FormFieldChildElement formFieldChildElement = provider.parse(parser, XmlEnvironment.from(parser, xmlEnvironment));
-                    break;
+                    builder.addFormFieldChildElement(formFieldChildElement);
-                case "value":
+                } else {
-                    formField.addValue(parser.nextText());
+                    LOGGER.warning("Unknown form field child element " + qname + " ignored");
-                    break;
-                case "required":
-                    formField.setRequired(true);
-                    break;
-                case "option":
-                    formField.addOption(parseOption(parser));
-                    break;
-                // See XEP-122 Data Forms Validation
-                case ValidateElement.ELEMENT:
-                    if (namespace.equals(ValidateElement.NAMESPACE)) {
-                        formField.setValidateElement(DataValidationProvider.parse(parser));
-                    }
-                    break;
                 }
                 break;
             case END_ELEMENT:
@@ -149,20 +148,23 @@ public class DataFormProvider extends ExtensionElementProvider<DataForm> {
                 break;
             }
         }
-        return formField;
+
+        return builder.build();
     }
 
-    private static DataForm.Item parseItem(XmlPullParser parser) throws XmlPullParserException, IOException {
+    private static DataForm.Item parseItem(XmlPullParser parser, XmlEnvironment xmlEnvironment)
+                    throws XmlPullParserException, IOException, SmackParsingException {
         final int initialDepth = parser.getDepth();
         List<FormField> fields = new ArrayList<>();
         outerloop: while (true) {
-            XmlPullParser.Event eventType = parser.next();
+            XmlPullParser.TagEvent eventType = parser.nextTag();
             switch (eventType) {
             case START_ELEMENT:
                 String name = parser.getName();
                 switch (name) {
                 case "field":
-                    fields.add(parseField(parser));
+                    FormField field = parseField(parser, XmlEnvironment.from(parser, xmlEnvironment));
+                    fields.add(field);
                     break;
                 }
                 break;
@@ -171,25 +173,24 @@ public class DataFormProvider extends ExtensionElementProvider<DataForm> {
                     break outerloop;
                 }
                 break;
-            default:
-                // Catch all for incomplete switch (MissingCasesInEnumSwitch) statement.
-                break;
             }
         }
         return new DataForm.Item(fields);
     }
 
-    private static DataForm.ReportedData parseReported(XmlPullParser parser) throws XmlPullParserException, IOException {
+    private static DataForm.ReportedData parseReported(XmlPullParser parser, XmlEnvironment xmlEnvironment)
+                    throws XmlPullParserException, IOException, SmackParsingException {
         final int initialDepth = parser.getDepth();
         List<FormField> fields = new ArrayList<>();
         outerloop: while (true) {
-            XmlPullParser.Event eventType = parser.next();
+            XmlPullParser.TagEvent eventType = parser.nextTag();
             switch (eventType) {
             case START_ELEMENT:
                 String name = parser.getName();
                 switch (name) {
                 case "field":
-                    fields.add(parseField(parser));
+                    FormField field = parseField(parser, XmlEnvironment.from(parser, xmlEnvironment));
+                    fields.add(field);
                     break;
                 }
                 break;
@@ -198,39 +199,9 @@ public class DataFormProvider extends ExtensionElementProvider<DataForm> {
                     break outerloop;
                 }
                 break;
-            default:
-                // Catch all for incomplete switch (MissingCasesInEnumSwitch) statement.
-                break;
             }
         }
         return new DataForm.ReportedData(fields);
     }
 
-    private static FormField.Option parseOption(XmlPullParser parser) throws XmlPullParserException, IOException {
-        final int initialDepth = parser.getDepth();
-        FormField.Option option = null;
-        String label = parser.getAttributeValue("", "label");
-        outerloop: while (true) {
-            XmlPullParser.Event eventType = parser.next();
-            switch (eventType) {
-            case START_ELEMENT:
-                String name = parser.getName();
-                switch (name) {
-                case "value":
-                    option = new FormField.Option(label, parser.nextText());
-                    break;
-                }
-                break;
-            case END_ELEMENT:
-                if (parser.getDepth() == initialDepth) {
-                    break outerloop;
-                }
-                break;
-            default:
-                // Catch all for incomplete switch (MissingCasesInEnumSwitch) statement.
-                break;
-            }
-        }
-        return option;
-    }
 }

smack-extensions/src/main/java/org/jivesoftware/smackx/xdata/provider/DescriptionProvider.java

@@ -0,0 +1,43 @@
+/**
+ *
+ * Copyright 2019 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.xdata.provider;
+
+import java.io.IOException;
+
+import javax.xml.namespace.QName;
+
+import org.jivesoftware.smack.packet.XmlEnvironment;
+import org.jivesoftware.smack.xml.XmlPullParser;
+import org.jivesoftware.smack.xml.XmlPullParserException;
+
+import org.jivesoftware.smackx.xdata.FormField;
+
+public class DescriptionProvider extends FormFieldChildElementProvider<FormField.Description> {
+
+    @Override
+    public FormField.Description parse(XmlPullParser parser, int initialDepth, XmlEnvironment xmlEnvironment)
+                    throws XmlPullParserException, IOException {
+        String description = parser.nextText();
+        return new FormField.Description(description);
+    }
+
+    @Override
+    public QName getQName() {
+        return FormField.Description.QNAME;
+    }
+
+}

smack-extensions/src/main/java/org/jivesoftware/smackx/xdata/provider/FormFieldChildElementProvider.java

@@ -0,0 +1,29 @@
+/**
+ *
+ * Copyright 2019 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.xdata.provider;
+
+import javax.xml.namespace.QName;
+
+import org.jivesoftware.smack.provider.Provider;
+
+import org.jivesoftware.smackx.xdata.FormFieldChildElement;
+
+public abstract class FormFieldChildElementProvider<F extends FormFieldChildElement> extends Provider<F> {
+
+    public abstract QName getQName();
+
+}

smack-extensions/src/main/java/org/jivesoftware/smackx/xdata/provider/FormFieldChildElementProviderManager.java

@@ -0,0 +1,45 @@
+/**
+ *
+ * Copyright 2019 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.xdata.provider;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+import javax.xml.namespace.QName;
+
+public class FormFieldChildElementProviderManager {
+
+    private static final Map<QName, FormFieldChildElementProvider<?>> providers = new ConcurrentHashMap<>();
+
+    public static void addFormFieldChildElementProvider(
+                    FormFieldChildElementProvider<?>... formFieldChildElementProviders) {
+        for (FormFieldChildElementProvider<?> formFieldChildElementProvider : formFieldChildElementProviders) {
+            QName qname = formFieldChildElementProvider.getQName();
+            providers.put(qname, formFieldChildElementProvider);
+        }
+    }
+
+    public static FormFieldChildElementProvider<?> addFormFieldChildElementProvider(QName qname,
+                    FormFieldChildElementProvider<?> formFieldChildElementProvider) {
+        return providers.put(qname, formFieldChildElementProvider);
+    }
+
+    public static FormFieldChildElementProvider<?> getFormFieldChildElementProvider(QName qname) {
+        return providers.get(qname);
+    }
+
+}

smack-extensions/src/main/java/org/jivesoftware/smackx/xdata/provider/OptionProvider.java

@@ -0,0 +1,63 @@
+/**
+ *
+ * Copyright 2019 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.xdata.provider;
+
+import java.io.IOException;
+
+import javax.xml.namespace.QName;
+
+import org.jivesoftware.smack.packet.XmlEnvironment;
+import org.jivesoftware.smack.parsing.SmackParsingException;
+import org.jivesoftware.smack.xml.XmlPullParser;
+import org.jivesoftware.smack.xml.XmlPullParserException;
+
+import org.jivesoftware.smackx.xdata.FormField;
+
+public class OptionProvider extends FormFieldChildElementProvider<FormField.Option> {
+
+    @Override
+    public FormField.Option parse(XmlPullParser parser, int initialDepth, XmlEnvironment xmlEnvironment)
+                    throws XmlPullParserException, IOException, SmackParsingException {
+        FormField.Option option = null;
+        String label = parser.getAttributeValue("", "label");
+        outerloop: while (true) {
+            XmlPullParser.TagEvent eventType = parser.nextTag();
+            switch (eventType) {
+            case START_ELEMENT:
+                String name = parser.getName();
+                switch (name) {
+                case "value":
+                    option = new FormField.Option(label, parser.nextText());
+                    break;
+                }
+                break;
+            case END_ELEMENT:
+                if (parser.getDepth() == initialDepth) {
+                    break outerloop;
+                }
+                break;
+            }
+        }
+        return option;
+    }
+
+    @Override
+    public QName getQName() {
+        return FormField.Option.QNAME;
+    }
+
+}

smack-extensions/src/main/java/org/jivesoftware/smackx/xdata/provider/RequiredProvider.java

@@ -0,0 +1,43 @@
+/**
+ *
+ * Copyright 2019 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.xdata.provider;
+
+import java.io.IOException;
+
+import javax.xml.namespace.QName;
+
+import org.jivesoftware.smack.packet.XmlEnvironment;
+import org.jivesoftware.smack.parsing.SmackParsingException;
+import org.jivesoftware.smack.xml.XmlPullParser;
+import org.jivesoftware.smack.xml.XmlPullParserException;
+
+import org.jivesoftware.smackx.xdata.FormField;
+
+public class RequiredProvider extends FormFieldChildElementProvider<FormField.Required> {
+
+    @Override
+    public FormField.Required parse(XmlPullParser parser, int initialDepth, XmlEnvironment xmlEnvironment)
+                    throws XmlPullParserException, IOException, SmackParsingException {
+        return FormField.Required.INSTANCE;
+    }
+
+    @Override
+    public QName getQName() {
+        return FormField.Required.QNAME;
+    }
+
+}

smack-extensions/src/main/java/org/jivesoftware/smackx/xdata/provider/ValueProvider.java

@@ -0,0 +1,43 @@
+/**
+ *
+ * Copyright 2019 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.xdata.provider;
+
+import java.io.IOException;
+
+import javax.xml.namespace.QName;
+
+import org.jivesoftware.smack.packet.XmlEnvironment;
+import org.jivesoftware.smack.xml.XmlPullParser;
+import org.jivesoftware.smack.xml.XmlPullParserException;
+
+import org.jivesoftware.smackx.xdata.FormField;
+
+public class ValueProvider extends FormFieldChildElementProvider<FormField.Value> {
+
+    @Override
+    public FormField.Value parse(XmlPullParser parser, int initialDepth, XmlEnvironment xmlEnvironment)
+                    throws XmlPullParserException, IOException {
+        String value = parser.nextText();
+        return new FormField.Value(value);
+    }
+
+    @Override
+    public QName getQName() {
+        return FormField.Value.QNAME;
+    }
+
+}

smack-extensions/src/main/java/org/jivesoftware/smackx/xdatavalidation/XDataValidationManager.java

@@ -21,11 +21,15 @@ import org.jivesoftware.smack.XMPPConnection;
 import org.jivesoftware.smack.XMPPConnectionRegistry;
 
 import org.jivesoftware.smackx.disco.ServiceDiscoveryManager;
+import org.jivesoftware.smackx.xdata.provider.FormFieldChildElementProviderManager;
 import org.jivesoftware.smackx.xdatavalidation.packet.ValidateElement;
+import org.jivesoftware.smackx.xdatavalidation.provider.DataValidationProvider;
 
 public class XDataValidationManager {
 
     static {
+        FormFieldChildElementProviderManager.addFormFieldChildElementProvider(new DataValidationProvider());
+
         XMPPConnectionRegistry.addConnectionCreationListener(new ConnectionCreationListener() {
             @Override
             public void connectionCreated(XMPPConnection connection) {

smack-extensions/src/main/java/org/jivesoftware/smackx/xdatavalidation/packet/ValidateElement.java

@@ -16,13 +16,15 @@
  */
 package org.jivesoftware.smackx.xdatavalidation.packet;
 
-import org.jivesoftware.smack.packet.ExtensionElement;
+import javax.xml.namespace.QName;
+
 import org.jivesoftware.smack.packet.NamedElement;
 import org.jivesoftware.smack.util.NumberUtil;
 import org.jivesoftware.smack.util.StringUtils;
 import org.jivesoftware.smack.util.XmlStringBuilder;
 
 import org.jivesoftware.smackx.xdata.FormField;
+import org.jivesoftware.smackx.xdata.FormFieldChildElement;
 import org.jivesoftware.smackx.xdata.packet.DataForm;
 import org.jivesoftware.smackx.xdatavalidation.ValidationConsistencyException;
 
@@ -34,12 +36,14 @@ import org.jivesoftware.smackx.xdatavalidation.ValidationConsistencyException;
  *
  * @author Anno van Vliet
  */
-public abstract class ValidateElement implements ExtensionElement {
+public abstract class ValidateElement implements FormFieldChildElement {
 
     public static final String DATATYPE_XS_STRING = "xs:string";
     public static final String ELEMENT = "validate";
     public static final String NAMESPACE = "http://jabber.org/protocol/xdata-validate";
 
+    public static final QName QNAME = new QName(NAMESPACE, ELEMENT);
+
     private final String datatype;
 
     private ListRange listRange;
@@ -82,9 +86,19 @@ public abstract class ValidateElement implements ExtensionElement {
         return NAMESPACE;
     }
 
+    @Override
+    public QName getQName() {
+        return QNAME;
+    }
+
+    @Override
+    public final boolean mustBeOnlyOfHisKind() {
+        return true;
+    }
+
     @Override
     public XmlStringBuilder toXML(org.jivesoftware.smack.packet.XmlEnvironment enclosingNamespace) {
-        XmlStringBuilder buf = new XmlStringBuilder(this);
+        XmlStringBuilder buf = new XmlStringBuilder(this, enclosingNamespace);
         buf.optAttribute("datatype", datatype);
         buf.rightAngleBracket();
         appendXML(buf);
@@ -115,11 +129,16 @@ public abstract class ValidateElement implements ExtensionElement {
     }
 
     /**
-     * Check if this element is consistent according to the business rules in XEP=0122.
+     * Check if this element is consistent according to the business rules in XEP-0122.
      *
-     * @param formField
+     * @param formFieldBuilder the builder used to construct the form field.
      */
-    public abstract void checkConsistency(FormField formField);
+    @Override
+    public abstract void checkConsistency(FormField.Builder formFieldBuilder);
+
+    public static ValidateElement from(FormField formField) {
+        return (ValidateElement) formField.getFormFieldChildElement(QNAME);
+    }
 
     /**
      * Validation only against the datatype itself. Indicates that the value(s) should simply match the field type and
@@ -146,7 +165,7 @@ public abstract class ValidateElement implements ExtensionElement {
         }
 
         @Override
-        public void checkConsistency(FormField formField) {
+        public void checkConsistency(FormField.Builder formField) {
             checkListRangeConsistency(formField);
             if (formField.getType() != null) {
                 switch (formField.getType()) {
@@ -189,7 +208,7 @@ public abstract class ValidateElement implements ExtensionElement {
         }
 
         @Override
-        public void checkConsistency(FormField formField) {
+        public void checkConsistency(FormField.Builder formField) {
             checkListRangeConsistency(formField);
             if (formField.getType() != null) {
                 switch (formField.getType()) {
@@ -257,7 +276,7 @@ public abstract class ValidateElement implements ExtensionElement {
         }
 
         @Override
-        public void checkConsistency(FormField formField) {
+        public void checkConsistency(FormField.Builder formField) {
             checkNonMultiConsistency(formField, METHOD);
             if (getDatatype().equals(ValidateElement.DATATYPE_XS_STRING)) {
                 throw new ValidationConsistencyException(String.format(
@@ -307,7 +326,7 @@ public abstract class ValidateElement implements ExtensionElement {
         }
 
         @Override
-        public void checkConsistency(FormField formField) {
+        public void checkConsistency(FormField.Builder formField) {
             checkNonMultiConsistency(formField, METHOD);
         }
 
@@ -385,7 +404,7 @@ public abstract class ValidateElement implements ExtensionElement {
      *
      * @param formField
      */
-    protected void checkListRangeConsistency(FormField formField) {
+    protected void checkListRangeConsistency(FormField.Builder formField) {
         ListRange listRange = getListRange();
         if (listRange == null) {
             return;
@@ -403,7 +422,7 @@ public abstract class ValidateElement implements ExtensionElement {
      * @param formField
      * @param method
      */
-    protected void checkNonMultiConsistency(FormField formField, String method) {
+    protected void checkNonMultiConsistency(FormField.Builder formField, String method) {
         checkListRangeConsistency(formField);
         if (formField.getType() != null) {
             switch (formField.getType()) {

smack-extensions/src/main/java/org/jivesoftware/smackx/xdatavalidation/provider/DataValidationProvider.java

@@ -19,10 +19,14 @@ package org.jivesoftware.smackx.xdatavalidation.provider;
 import java.io.IOException;
 import java.util.logging.Logger;
 
+import javax.xml.namespace.QName;
+
+import org.jivesoftware.smack.packet.XmlEnvironment;
 import org.jivesoftware.smack.util.ParserUtils;
 import org.jivesoftware.smack.xml.XmlPullParser;
 import org.jivesoftware.smack.xml.XmlPullParserException;
 
+import org.jivesoftware.smackx.xdata.provider.FormFieldChildElementProvider;
 import org.jivesoftware.smackx.xdatavalidation.packet.ValidateElement;
 import org.jivesoftware.smackx.xdatavalidation.packet.ValidateElement.BasicValidateElement;
 import org.jivesoftware.smackx.xdatavalidation.packet.ValidateElement.ListRange;
@@ -36,11 +40,12 @@ import org.jivesoftware.smackx.xdatavalidation.packet.ValidateElement.RegexValid
  * @author Anno van Vliet
  *
  */
-public class DataValidationProvider {
+public class DataValidationProvider extends FormFieldChildElementProvider<ValidateElement> {
     private static final Logger LOGGER = Logger.getLogger(DataValidationProvider.class.getName());
 
-    public static ValidateElement parse(XmlPullParser parser) throws XmlPullParserException, IOException {
+    @Override
-        final int initialDepth = parser.getDepth();
+    public ValidateElement parse(XmlPullParser parser, int initialDepth, XmlEnvironment xmlEnvironment)
+                    throws XmlPullParserException, IOException {
         final String dataType = parser.getAttributeValue("", "datatype");
         ValidateElement dataValidation = null;
         ListRange listRange = null;
@@ -98,4 +103,9 @@ public class DataValidationProvider {
         return dataValidation;
     }
 
+    @Override
+    public QName getQName() {
+        return ValidateElement.QNAME;
+    }
+
 }

smack-extensions/src/test/java/org/jivesoftware/smackx/caps/EntityCapsManagerTest.java

@@ -117,31 +117,31 @@ public class EntityCapsManagerTest extends InitExtensions {
 
         DataForm df = new DataForm(DataForm.Type.result);
 
-        FormField ff = new FormField("os");
+        FormField.Builder ff = FormField.builder("os");
         ff.addValue("Mac");
-        df.addField(ff);
+        df.addField(ff.build());
 
-        ff = new FormField("FORM_TYPE");
+        ff = FormField.builder("FORM_TYPE");
         ff.setType(FormField.Type.hidden);
         ff.addValue("urn:xmpp:dataforms:softwareinfo");
-        df.addField(ff);
+        df.addField(ff.build());
 
-        ff = new FormField("ip_version");
+        ff = FormField.builder("ip_version");
         ff.addValue("ipv4");
         ff.addValue("ipv6");
-        df.addField(ff);
+        df.addField(ff.build());
 
-        ff = new FormField("os_version");
+        ff = FormField.builder("os_version");
         ff.addValue("10.5.1");
-        df.addField(ff);
+        df.addField(ff.build());
 
-        ff = new FormField("software");
+        ff = FormField.builder("software");
         ff.addValue("Psi");
-        df.addField(ff);
+        df.addField(ff.build());
 
-        ff = new FormField("software_version");
+        ff = FormField.builder("software_version");
         ff.addValue("0.11");
-        df.addField(ff);
+        df.addField(ff.build());
 
         di.addExtension(df);
         return di;
@@ -174,31 +174,31 @@ public class EntityCapsManagerTest extends InitExtensions {
 
         DataForm df = new DataForm(DataForm.Type.result);
 
-        FormField ff = new FormField("os");
+        FormField.Builder ff = FormField.builder("os");
         ff.addValue("Mac");
-        df.addField(ff);
+        df.addField(ff.build());
 
-        ff = new FormField("FORM_TYPE");
+        ff = FormField.builder("FORM_TYPE");
         ff.setType(FormField.Type.hidden);
         ff.addValue("urn:xmpp:dataforms:softwareinfo");
-        df.addField(ff);
+        df.addField(ff.build());
 
-        ff = new FormField("ip_version");
+        ff = FormField.builder("ip_version");
         ff.addValue("ipv4");
         ff.addValue("ipv6");
-        df.addField(ff);
+        df.addField(ff.build());
 
-        ff = new FormField("os_version");
+        ff = FormField.builder("os_version");
         ff.addValue("10.5.1");
-        df.addField(ff);
+        df.addField(ff.build());
 
-        ff = new FormField("software");
+        ff = FormField.builder("software");
         ff.addValue("Psi");
-        df.addField(ff);
+        df.addField(ff.build());
 
-        ff = new FormField("software_version");
+        ff = FormField.builder("software_version");
         ff.addValue("0.11");
-        df.addField(ff);
+        df.addField(ff.build());
 
         di.addExtension(df);
 
@@ -206,14 +206,14 @@ public class EntityCapsManagerTest extends InitExtensions {
         // FORM_TYPE
         df = new DataForm(DataForm.Type.result);
 
-        ff = new FormField("FORM_TYPE");
+        ff = FormField.builder("FORM_TYPE");
         ff.setType(FormField.Type.hidden);
         ff.addValue("urn:xmpp:dataforms:softwareinfo");
-        df.addField(ff);
+        df.addField(ff.build());
 
-        ff = new FormField("software");
+        ff = FormField.builder("software");
         ff.addValue("smack");
-        df.addField(ff);
+        df.addField(ff.build());
 
         di.addExtension(df);
 

smack-extensions/src/test/java/org/jivesoftware/smackx/muc/RoomInfoTest.java

@@ -42,17 +42,17 @@ public class RoomInfoTest {
     public void validateRoomWithForm() {
         DataForm dataForm = new DataForm(DataForm.Type.result);
 
-        FormField desc = new FormField("muc#roominfo_description");
+        FormField.Builder desc = FormField.builder("muc#roominfo_description");
         desc.addValue("The place for all good witches!");
-        dataForm.addField(desc);
+        dataForm.addField(desc.build());
 
-        FormField subject = new FormField("muc#roominfo_subject");
+        FormField.Builder subject = FormField.builder("muc#roominfo_subject");
         subject.addValue("Spells");
-        dataForm.addField(subject);
+        dataForm.addField(subject.build());
 
-        FormField occupants = new FormField("muc#roominfo_occupants");
+        FormField.Builder occupants = FormField.builder("muc#roominfo_occupants");
         occupants.addValue("3");
-        dataForm.addField(occupants);
+        dataForm.addField(occupants.build());
 
         DiscoverInfo discoInfo = new DiscoverInfo();
         discoInfo.addExtension(dataForm);

smack-extensions/src/test/java/org/jivesoftware/smackx/xdata/packet/DataFormTest.java

@@ -20,6 +20,7 @@ import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
 
 import org.jivesoftware.smack.packet.Element;
+import org.jivesoftware.smack.test.util.SmackTestSuite;
 import org.jivesoftware.smack.util.PacketParserUtils;
 import org.jivesoftware.smack.xml.XmlPullParser;
 
@@ -41,9 +42,9 @@ import org.junit.Test;
  * @author Anno van Vliet
  *
  */
-public class DataFormTest {
+public class DataFormTest extends SmackTestSuite {
-    private static final String TEST_OUTPUT_1 = "<x xmlns='jabber:x:data' type='submit'><instructions>InstructionTest1</instructions><field var='testField1'></field></x>";
+    private static final String TEST_OUTPUT_1 = "<x xmlns='jabber:x:data' type='submit'><instructions>InstructionTest1</instructions><field var='testField1'/></x>";
-    private static final String TEST_OUTPUT_2 = "<x xmlns='jabber:x:data' type='submit'><instructions>InstructionTest1</instructions><field var='testField1'></field><page xmlns='http://jabber.org/protocol/xdata-layout' label='Label'><fieldref var='testField1'/><section label='section Label'><text>SectionText</text></section><text>PageText</text></page></x>";
+    private static final String TEST_OUTPUT_2 = "<x xmlns='jabber:x:data' type='submit'><instructions>InstructionTest1</instructions><field var='testField1'/><page xmlns='http://jabber.org/protocol/xdata-layout' label='Label'><fieldref var='testField1'/><section label='section Label'><text>SectionText</text></section><text>PageText</text></page></x>";
     private static final String TEST_OUTPUT_3 = "<x xmlns='jabber:x:data' type='submit'><instructions>InstructionTest1</instructions><field var='testField1'><validate xmlns='http://jabber.org/protocol/xdata-validate' datatype='xs:integer'><range min='1111' max='9999'/></validate></field></x>";
 
     private static final DataFormProvider pr = new DataFormProvider();
@@ -54,7 +55,7 @@ public class DataFormTest {
         DataForm df = new DataForm(DataForm.Type.submit);
         String instruction = "InstructionTest1";
         df.addInstruction(instruction);
-        FormField field = new FormField("testField1");
+        FormField field = FormField.builder("testField1").build();
         df.addField(field);
 
         assertNotNull(df.toXML());
@@ -81,7 +82,7 @@ public class DataFormTest {
         DataForm df = new DataForm(DataForm.Type.submit);
         String instruction = "InstructionTest1";
         df.addInstruction(instruction);
-        FormField field = new FormField("testField1");
+        FormField field = FormField.builder("testField1").build();
         df.addField(field);
 
         DataLayout layout = new DataLayout("Label");
@@ -123,11 +124,12 @@ public class DataFormTest {
         DataForm df = new DataForm(DataForm.Type.submit);
         String instruction = "InstructionTest1";
         df.addInstruction(instruction);
-        FormField field = new FormField("testField1");
+        FormField.Builder fieldBuilder = FormField.builder("testField1");
-        df.addField(field);
 
         ValidateElement dv = new RangeValidateElement("xs:integer", "1111", "9999");
-        field.setValidateElement(dv);
+        fieldBuilder.addFormFieldChildElement(dv);
+
+        df.addField(fieldBuilder.build());
 
         assertNotNull(df.toXML());
         String output = df.toXML().toString();
@@ -140,7 +142,7 @@ public class DataFormTest {
         assertNotNull(df);
         assertNotNull(df.getFields());
         assertEquals(1 , df.getFields().size());
-        Element element = df.getFields().get(0).getValidateElement();
+        Element element = ValidateElement.from(df.getFields().get(0));
         assertNotNull(element);
         dv = (ValidateElement) element;
 

smack-extensions/src/test/java/org/jivesoftware/smackx/xdatavalidation/DataValidationHelperTest.java

@@ -17,7 +17,7 @@
 package org.jivesoftware.smackx.xdatavalidation;
 
 import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.fail;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 import org.jivesoftware.smackx.xdata.FormField;
 import org.jivesoftware.smackx.xdatavalidation.packet.ValidateElement.BasicValidateElement;
@@ -26,7 +26,7 @@ import org.jivesoftware.smackx.xdatavalidation.packet.ValidateElement.OpenValida
 import org.jivesoftware.smackx.xdatavalidation.packet.ValidateElement.RangeValidateElement;
 import org.jivesoftware.smackx.xdatavalidation.packet.ValidateElement.RegexValidateElement;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 /**
  * Data validation helper test.
@@ -35,81 +35,55 @@ import org.junit.Test;
  */
 public class DataValidationHelperTest {
 
-
     @Test
     public void testCheckConsistencyFormFieldBasicValidateElement() {
-        FormField field = new FormField("var");
+        FormField.Builder field = FormField.builder("var")
-        field.setType(FormField.Type.jid_single);
+                        .setType(FormField.Type.jid_single);
         BasicValidateElement element = new BasicValidateElement(null);
-        try {
+        ValidationConsistencyException vce = assertThrows(ValidationConsistencyException.class,
-            element.checkConsistency(field);
+                        () -> element.checkConsistency(field));
-            fail("No correct check on consistency");
+        assertEquals("Field type 'jid-single' is not consistent with validation method 'basic'.", vce.getMessage());
-        }
-        catch (ValidationConsistencyException e) {
-            assertEquals("Field type 'jid-single' is not consistent with validation method 'basic'.", e.getMessage());
-        }
 
-        try {
+        IllegalArgumentException iae = assertThrows(IllegalArgumentException.class,
-            new ListRange(-1L, 1L);
+                        () -> new ListRange(-1L, 1L));
-            fail("No correct check on consistency");
+        assertEquals("unsigned 32-bit integers can't be negative", iae.getMessage());
-        }
-        catch (IllegalArgumentException e) {
-            assertEquals("unsigned 32-bit integers can't be negative", e.getMessage());
-        }
 
         element.setListRange(new ListRange(10L, 100L));
-        try {
+        vce = assertThrows(ValidationConsistencyException.class, () -> element.checkConsistency(field));
-            element.checkConsistency(field);
+        assertEquals("Field type is not of type 'list-multi' while a 'list-range' is defined.", vce.getMessage());
-            fail("No correct check on consistency");
-        }
-        catch (ValidationConsistencyException e) {
-            assertEquals("Field type is not of type 'list-multi' while a 'list-range' is defined.", e.getMessage());
-        }
 
-        field.setType(FormField.Type.list_multi);
+        FormField.Builder fieldListMulti = field.setType(FormField.Type.list_multi);
-        element.checkConsistency(field);
+        element.checkConsistency(fieldListMulti);
     }
 
 
     @Test
     public void testCheckConsistencyFormFieldOpenValidateElement() {
-        FormField field = new FormField("var");
+        FormField.Builder field = FormField.builder("var")
-        field.setType(FormField.Type.hidden);
+                        .setType(FormField.Type.hidden);
         OpenValidateElement element = new OpenValidateElement(null);
-        try {
+        ValidationConsistencyException e = assertThrows(ValidationConsistencyException.class,
-            element.checkConsistency(field);
+                        () -> element.checkConsistency(field));
-            fail("No correct check on consistency");
+        assertEquals("Field type 'hidden' is not consistent with validation method 'open'.", e.getMessage());
-        }
-        catch (ValidationConsistencyException e) {
-            assertEquals("Field type 'hidden' is not consistent with validation method 'open'.", e.getMessage());
-        }
     }
 
     @Test
     public void testCheckConsistencyFormFieldRangeValidateElement() {
-        FormField field = new FormField("var");
+        FormField.Builder field = FormField.builder("var")
-        field.setType(FormField.Type.text_multi);
+                        .setType(FormField.Type.text_multi);
         RangeValidateElement element = new RangeValidateElement("xs:integer", null,  "99");
-        try {
+        ValidationConsistencyException e = assertThrows(ValidationConsistencyException.class,
-            element.checkConsistency(field);
+                        () -> element.checkConsistency(field));
-            fail("No correct check on consistency");
+        assertEquals("Field type 'text-multi' is not consistent with validation method 'range'.", e.getMessage());
-        }
-        catch (ValidationConsistencyException e) {
-            assertEquals("Field type 'text-multi' is not consistent with validation method 'range'.", e.getMessage());
-        }
     }
 
     @Test
     public void testCheckConsistencyFormFieldRegexValidateElement() {
-        FormField field = new FormField("var");
+        FormField.Builder field = FormField.builder("var")
-        field.setType(FormField.Type.list_multi);
+                        .setType(FormField.Type.list_multi);
         RegexValidateElement element = new RegexValidateElement(null, ".*");
-        try {
+        ValidationConsistencyException e = assertThrows(ValidationConsistencyException.class,
-            element.checkConsistency(field);
+                        () -> element.checkConsistency(field));
-            fail("No correct check on consistency");
+        assertEquals("Field type 'list-multi' is not consistent with validation method 'regex'.", e.getMessage());
-        }
-        catch (ValidationConsistencyException e) {
-            assertEquals("Field type 'list-multi' is not consistent with validation method 'regex'.", e.getMessage());
-        }
     }
 }

smack-extensions/src/test/java/org/jivesoftware/smackx/xdatavalidation/provider/DataValidationTest.java

@@ -19,12 +19,13 @@ package org.jivesoftware.smackx.xdatavalidation.provider;
  import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 import java.io.IOException;
 
+import org.jivesoftware.smack.parsing.SmackParsingException;
+import org.jivesoftware.smack.test.util.SmackTestSuite;
 import org.jivesoftware.smack.test.util.SmackTestUtil;
-import org.jivesoftware.smack.test.util.TestUtils;
-import org.jivesoftware.smack.xml.XmlPullParser;
 import org.jivesoftware.smack.xml.XmlPullParserException;
 
 import org.jivesoftware.smackx.xdata.FormField;
@@ -35,7 +36,7 @@ import org.jivesoftware.smackx.xdatavalidation.packet.ValidateElement.BasicValid
 import org.jivesoftware.smackx.xdatavalidation.packet.ValidateElement.ListRange;
 import org.jivesoftware.smackx.xdatavalidation.packet.ValidateElement.RangeValidateElement;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.EnumSource;
 
@@ -44,7 +45,7 @@ import org.junit.jupiter.params.provider.EnumSource;
  * @author Anno van Vliet
  *
  */
-public class DataValidationTest {
+public class DataValidationTest extends SmackTestSuite {
     private static final String TEST_INPUT_MIN = "<validate xmlns='http://jabber.org/protocol/xdata-validate'></validate>";
     private static final String TEST_OUTPUT_MIN = "<validate xmlns='http://jabber.org/protocol/xdata-validate'><basic/></validate>";
     private static final String TEST_OUTPUT_RANGE = "<validate xmlns='http://jabber.org/protocol/xdata-validate' datatype='xs:string'><range min='min-val' max='max-val'/><list-range min='111' max='999'/></validate>";
@@ -52,42 +53,50 @@ public class DataValidationTest {
     private static final String TEST_OUTPUT_FAIL = "<validate xmlns='http://jabber.org/protocol/xdata-validate'><list-range min='1-1-1' max='999'/></validate>";
 
     @Test
-    public void testMin() throws XmlPullParserException, IOException {
+    public void testBasic() {
-
         ValidateElement dv = new BasicValidateElement(null);
 
         assertNotNull(dv.toXML());
         String output = dv.toXML().toString();
         assertEquals(TEST_OUTPUT_MIN, output);
+    }
 
-        XmlPullParser parser = getParser(TEST_INPUT_MIN);
+    @ParameterizedTest
-
+    @EnumSource(SmackTestUtil.XmlPullParserKind.class)
-        dv = DataValidationProvider.parse(parser);
+    public void testMin(SmackTestUtil.XmlPullParserKind parserKind) throws XmlPullParserException, IOException, SmackParsingException {
+        ValidateElement dv = SmackTestUtil.parse(TEST_INPUT_MIN, DataValidationProvider.class, parserKind);
 
         assertNotNull(dv);
         assertEquals("xs:string", dv.getDatatype());
         assertTrue(dv instanceof BasicValidateElement);
 
         assertNotNull(dv.toXML());
-        output = dv.toXML().toString();
+        String output = dv.toXML().toString();
         assertEquals(TEST_OUTPUT_MIN, output);
     }
 
     @Test
-    public void testRange() throws XmlPullParserException, IOException {
+    public void testRangeToXml() {
-
         ValidateElement dv = new RangeValidateElement("xs:string", "min-val", "max-val");
-
         ListRange listRange = new ListRange(111L, 999L);
         dv.setListRange(listRange);
 
         assertNotNull(dv.toXML());
         String output = dv.toXML().toString();
         assertEquals(TEST_OUTPUT_RANGE, output);
+    }
 
-        XmlPullParser parser = getParser(output);
+    @ParameterizedTest
+    @EnumSource(SmackTestUtil.XmlPullParserKind.class)
+    public void testRange(SmackTestUtil.XmlPullParserKind parserKind)
+                    throws XmlPullParserException, IOException, SmackParsingException {
+        ValidateElement dv = new RangeValidateElement("xs:string", "min-val", "max-val");
+        ListRange listRange = new ListRange(111L, 999L);
+        dv.setListRange(listRange);
 
-        dv = DataValidationProvider.parse(parser);
+        String xml = dv.toXML().toString();
+
+        dv = SmackTestUtil.parse(xml, DataValidationProvider.class, parserKind);
 
         assertNotNull(dv);
         assertEquals("xs:string", dv.getDatatype());
@@ -99,24 +108,27 @@ public class DataValidationTest {
         assertEquals(Long.valueOf(111), rdv.getListRange().getMin());
         assertEquals(999, rdv.getListRange().getMax().intValue());
 
-
         assertNotNull(dv.toXML());
-        output = dv.toXML().toString();
+        xml = dv.toXML().toString();
-        assertEquals(TEST_OUTPUT_RANGE, output);
+        assertEquals(TEST_OUTPUT_RANGE, xml);
     }
 
     @Test
-    public void testRange2() throws XmlPullParserException, IOException {
+    public void testRange2ToXml() {
-
         ValidateElement dv = new RangeValidateElement(null, null, null);
 
         assertNotNull(dv.toXML());
         String output = dv.toXML().toString();
         assertEquals(TEST_OUTPUT_RANGE2, output);
+    }
 
-        XmlPullParser parser = getParser(output);
+    @ParameterizedTest
+    @EnumSource(SmackTestUtil.XmlPullParserKind.class)
+    public void testRange2(SmackTestUtil.XmlPullParserKind parserKind) throws XmlPullParserException, IOException, SmackParsingException {
+        ValidateElement dv = new RangeValidateElement(null, null, null);
+        String xml = dv.toXML().toString();
 
-        dv = DataValidationProvider.parse(parser);
+        dv = SmackTestUtil.parse(xml, DataValidationProvider.class, parserKind);
 
         assertNotNull(dv);
         assertEquals("xs:string", dv.getDatatype());
@@ -126,14 +138,15 @@ public class DataValidationTest {
         assertEquals(null, rdv.getMax());
 
         assertNotNull(rdv.toXML());
-        output = rdv.toXML().toString();
+        xml = rdv.toXML().toString();
-        assertEquals(TEST_OUTPUT_RANGE2, output);
+        assertEquals(TEST_OUTPUT_RANGE2, xml);
     }
 
-    @Test(expected = NumberFormatException.class)
+    @ParameterizedTest
-    public void testRangeFailure() throws IOException, XmlPullParserException {
+    @EnumSource(SmackTestUtil.XmlPullParserKind.class)
-            XmlPullParser parser = getParser(TEST_OUTPUT_FAIL);
+    public void testRangeFailure(SmackTestUtil.XmlPullParserKind parserKind) throws IOException, XmlPullParserException {
-            DataValidationProvider.parse(parser);
+        assertThrows(NumberFormatException.class,
+                        () -> SmackTestUtil.parse(TEST_OUTPUT_FAIL, DataValidationProvider.class, parserKind));
     }
 
     @ParameterizedTest
@@ -168,18 +181,8 @@ public class DataValidationTest {
         assertEquals("Event Name", nameField.getLabel());
 
         FormField dataStartField = dataForm.getField("date/start");
-        ValidateElement dataStartValidateElement = dataStartField.getValidateElement();
+        ValidateElement dataStartValidateElement = ValidateElement.from(dataStartField);
         assertEquals("xs:date", dataStartValidateElement.getDatatype());
         assertTrue(dataStartValidateElement instanceof BasicValidateElement);
     }
-
-    /**
-     * @param output
-     * @return
-     * @throws XmlPullParserException
-     * @throws IOException
-     */
-    private static XmlPullParser getParser(String output) throws XmlPullParserException, IOException {
-        return TestUtils.getParser(output, "validate");
-    }
 }

smack-integration-test/src/main/java/org/jivesoftware/smackx/xdata/FormTest.java

@@ -25,7 +25,7 @@ import org.jivesoftware.smack.SmackException.NotConnectedException;
 import org.jivesoftware.smack.StanzaCollector;
 import org.jivesoftware.smack.filter.ThreadFilter;
 import org.jivesoftware.smack.packet.Message;
-
+import org.jivesoftware.smackx.xdata.FormField.Type;
 import org.jivesoftware.smackx.xdata.packet.DataForm;
 
 import org.igniterealtime.smack.inttest.AbstractSmackIntegrationTest;
@@ -59,34 +59,35 @@ public class FormTest extends AbstractSmackIntegrationTest {
             "Fill out this form to report your case.\nThe case will be created automatically.");
         formToSend.setTitle("Case configurations");
         // Add a hidden variable
-        FormField field = new FormField("hidden_var");
+        FormField.Builder field = FormField.builder("hidden_var");
         field.setType(FormField.Type.hidden);
         field.addValue("Some value for the hidden variable");
-        formToSend.addField(field);
+        formToSend.addField(field.build());
         // Add a fixed variable
-        field = new FormField();
+        field = FormField.builder();
         field.addValue("Section 1: Case description");
-        formToSend.addField(field);
+        field.setType(Type.fixed);
+        formToSend.addField(field.build());
         // Add a text-single variable
-        field = new FormField("name");
+        field = FormField.builder("name");
         field.setLabel("Enter a name for the case");
         field.setType(FormField.Type.text_single);
-        formToSend.addField(field);
+        formToSend.addField(field.build());
         // Add a text-multi variable
-        field = new FormField("description");
+        field = FormField.builder("description");
         field.setLabel("Enter a description");
         field.setType(FormField.Type.text_multi);
-        formToSend.addField(field);
+        formToSend.addField(field.build());
         // Add a boolean variable
-        field = new FormField("time");
+        field = FormField.builder("time");
         field.setLabel("Is this your first case?");
         field.setType(FormField.Type.bool);
-        formToSend.addField(field);
+        formToSend.addField(field.build());
         // Add a text variable where an int value is expected
-        field = new FormField("age");
+        field = FormField.builder("age");
         field.setLabel("How old are you?");
         field.setType(FormField.Type.text_single);
-        formToSend.addField(field);
+        formToSend.addField(field.build());
 
         // Create the chats between the two participants
         org.jivesoftware.smack.chat.Chat chat = org.jivesoftware.smack.chat.ChatManager.getInstanceFor(conOne).createChat(conTwo.getUser(), null);

smack-legacy/src/main/java/org/jivesoftware/smackx/workgroup/user/Workgroup.java

@@ -403,9 +403,9 @@ public class Workgroup {
             String name = iter.next();
             String value = metadata.get(name).toString();
 
-            FormField field = new FormField(name);
+            FormField.Builder field = FormField.builder(name);
             field.setType(FormField.Type.text_single);
-            form.addField(field);
+            form.addField(field.build());
             form.setAnswer(name, value);
         }
         joinQueue(form, userID);