[pubsub] Allow for character data before <item/>'s payload

Fixes SMACK-918.

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

@@ -50,12 +50,9 @@ public class ItemProvider extends ExtensionElementProvider<Item>  {
         String xmlns = parser.getNamespace();
         ItemNamespace itemNamespace = ItemNamespace.fromXmlns(xmlns);
 
-        XmlPullParser.Event tag = parser.next();
+        XmlPullParser.TagEvent event = parser.nextTag();
-
+        switch (event) {
-        if (tag == XmlPullParser.Event.END_ELEMENT)  {
+            case START_ELEMENT:
-            return new Item(itemNamespace, id, node);
-        }
-        else {
                 String payloadElemName = parser.getName();
                 String payloadNS = parser.getNamespace();
 
@@ -68,6 +65,10 @@ public class ItemProvider extends ExtensionElementProvider<Item>  {
                 else {
                     return new PayloadItem<>(itemNamespace, id, node, extensionProvider.parse(parser));
                 }
+            case END_ELEMENT:
+                return new Item(itemNamespace, id, node);
+            default:
+                throw new AssertionError("unknown: " + event);
         }
     }
 

smack-extensions/src/test/java/org/jivesoftware/smackx/pubsub/provider/ItemProviderTest.java

@@ -0,0 +1,48 @@
+/**
+ *
+ * Copyright 2021 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.pubsub.provider;
+
+import java.io.IOException;
+
+import org.jivesoftware.smack.parsing.SmackParsingException;
+import org.jivesoftware.smack.test.util.SmackTestUtil;
+import org.jivesoftware.smack.xml.XmlPullParserException;
+
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.EnumSource;
+
+public class ItemProviderTest {
+
+    /**
+     * Check that {@link ItemProvider} is able to parse items which have whitespace before their Payload.
+     *
+     * @param parserKind the used parser Kind
+     * @throws XmlPullParserException if an XML pull parser exception occurs.
+     * @throws IOException if an IO exception occurs.
+     * @throws SmackParsingException if an Smack parsing exception occurs.
+     * @see <a href="https://igniterealtime.atlassian.net/jira/software/c/projects/SMACK/issues/SMACK-918">SMACK-918</a>
+     */
+    @ParameterizedTest
+    @EnumSource(SmackTestUtil.XmlPullParserKind.class)
+    public void whitespaceBeforeItemPayload(SmackTestUtil.XmlPullParserKind parserKind) throws XmlPullParserException, IOException, SmackParsingException {
+        String item = "<item id='13a3710c-68c3-4da2-8484-d8d9c77af91e' xmlns='http://jabber.org/protocol/pubsub#event'>"
+                    + "\n <geoloc xmlns='http://jabber.org/protocol/geoloc' xml:lang='en'/>"
+                    + "</item>";
+        SmackTestUtil.parse(item, ItemProvider.class, parserKind);
+    }
+
+}