Fix XMPP plugin for parser changes.

parser_xmpp/src/com/dmdirc/addons/parser_xmpp/XmppClientInfo.java

 
 import com.dmdirc.parser.common.AwayState;
 import com.dmdirc.parser.common.BaseClientInfo;
+import com.dmdirc.parser.interfaces.ChannelClientInfo;
+
+import com.google.common.collect.Lists;
 
 import java.util.ArrayList;
 import java.util.Collections;
         return 0;
     }
 
+    @Override
+    public List<ChannelClientInfo> getChannelClients() {
+        return Lists.newArrayList();
+    }
+
     /**
      * Retrieves the map of known endpoints for this client.
      *