Fix parsing of SSE topic for groups (openhab#3503)

There can be an optional group in the topic path.

Signed-off-by: mueller-ma <[email protected]>

mobile/src/main/java/org/openhab/habdroid/background/ItemsControlsProviderService.kt

@@ -97,7 +97,13 @@ class ItemsControlsProviderService : ControlsProviderService() {
                     }
                     val topic = event.getString("topic")
                     val topicPath = topic.split('/')
-                    if (topicPath.size != 4) {
+                    /* Possible formats:
+                    * - openhab/items/<item>/statechanged
+                    * - openhab/items/<group item>/<item>/statechanged
+                    * When an update for a group is sent, there's also one for the individual item.
+                    * Therefore always take the element on index two.
+                    */
+                    if (topicPath.size !in intArrayOf(4, 5)) {
                         throw JSONException("Unexpected topic path $topic")
                     }
                     val item = allItems[topicPath[2]]