Dispatch commands on main thread when run from XMPP (EssentialsX#3803)

This PR fixes an issue reported on Discord, where commands executed through XMPP are dispatched async from the XMPP listener thread.

Author: mdcfe

EssentialsXMPP/src/main/java/com/earth2me/essentials/xmpp/XMPPManager.java

@@ -320,11 +320,13 @@ private void sendPrivateMessage(final Chat chat, final String message) {
 
     private void sendCommand(final Chat chat, final String message) {
         if (config.getStringList("op-users").contains(StringUtils.parseBareAddress(chat.getParticipant()))) {
-            try {
-                parent.getServer().dispatchCommand(Console.getInstance().getCommandSender(), message.substring(1));
-            } catch (final Exception ex) {
-                logger.log(Level.SEVERE, ex.getMessage(), ex);
-            }
+            parent.getServer().getScheduler().runTask(parent, () -> {
+                try {
+                    parent.getServer().dispatchCommand(Console.getInstance().getCommandSender(), message.substring(1));
+                } catch (final Exception ex) {
+                    logger.log(Level.SEVERE, ex.getMessage(), ex);
+                }
+            });
         }
     }