Enfore spaces for indentation

Although I'm in the tabs camp, Smack uses mostly spaces. Therefore it
is the logical choice for the indentation style.

config/checkstyle.xml

@@ -35,10 +35,6 @@
 		<property name="format" value="^\s+$"/>
 		<property name="message" value="Line containing only whitespace character(s)"/>
 	</module>
-	<module name="RegexpSingleline">
-		<property name="format" value="^ +\t+"/>
-		<property name="message" value="Line containing tab(s) after space"/>
-	</module>
 	<module name="RegexpSingleline">
 		<!-- We use {2,} instead of + here to address the typical case where a file was written
 		   with tabs but javadoc is causing '\t *' -->
@@ -89,6 +85,10 @@
 			<property name="message" value="Usage of println"/>
 			<property name="ignoreComments" value="true"/>
 		</module>
+		<module name="RegexpSinglelineJava">
+			<property name="format" value="^\t+"/>
+			<property name="message" value="Indent must not use tab characters. Use space instead."/>
+		</module>
 		<module name="JavadocMethod">
 			<!-- TODO stricten those checks -->
 			<property name="scope" value="public"/>

smack-android-extensions/src/main/java/org/jivesoftware/smackx/ping/android/ServerPingWithAlarmManager.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright © 2014 Florian Schmaus
+ * Copyright © 2014-2017 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

smack-android/src/main/java/org/jivesoftware/smack/android/AndroidSmackInitializer.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright © 2014 Florian Schmaus
+ * Copyright © 2014-2017 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

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

@@ -91,9 +91,7 @@ public class Item extends NodeExtension
      */
     public Item(String itemId, String nodeId)
     {
-    // CHECKSTYLE:OFF
         super(PubSubElementType.ITEM_EVENT, nodeId);
-    // CHECKSTYLE:ON
         id = itemId;
     }
 

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

@@ -366,9 +366,7 @@ abstract public class Node
      */
     public Subscription subscribe(String jid) throws NoResponseException, XMPPErrorException, NotConnectedException, InterruptedException
     {
-// CHECKSTYLE:OFF
         PubSub pubSub = createPubsubPacket(Type.set, new SubscribeExtension(jid, getId()));
-// CHECKSTYLE:ON
         PubSub reply = sendPubsubPacket(pubSub);
         return reply.getExtension(PubSubElementType.SUBSCRIPTION);
     }
@@ -394,9 +392,7 @@ abstract public class Node
      */
     public Subscription subscribe(String jid, SubscribeForm subForm) throws NoResponseException, XMPPErrorException, NotConnectedException, InterruptedException
     {
-// CHECKSTYLE:OFF
         PubSub request = createPubsubPacket(Type.set, new SubscribeExtension(jid, getId()));
-// CHECKSTYLE:ON
         request.addExtension(new FormNode(FormNodeType.OPTIONS, subForm));
         PubSub reply = sendPubsubPacket(request);
         return reply.getExtension(PubSubElementType.SUBSCRIPTION);

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

@@ -36,8 +36,6 @@ public class EventProvider extends EmbeddedExtensionProvider<EventElement>
     @Override
     protected EventElement createReturnExtension(String currentElement, String currentNamespace, Map<String, String> attMap, List<? extends ExtensionElement> content)
     {
-// CHECKSTYLE:OFF
         return new EventElement(EventElementType.valueOf(content.get(0).getElementName()), (NodeExtension)content.get(0));
-// CHECKSTYLE:ON
     }
 }