Fixed PadAddListener with right content type

src/main/scala/de/tobias/playpad/server/server/project/sync/listener/pad/PadAddListener.scala

@@ -22,6 +22,10 @@ class PadAddListener extends Listener {
 		SqlHelper.insertOrUpdate(connection, SqlDef.PAD, padId, SqlDef.PAD_PAGE_REF, pageId)
 		SqlHelper.insertOrUpdate(connection, SqlDef.PAD, padId, SqlDef.PAD_NAME, padName)
 		SqlHelper.insertOrUpdate(connection, SqlDef.PAD, padId, SqlDef.PAD_POSITION, padPosition)
-		SqlHelper.insertOrUpdate(connection, SqlDef.PAD, padId, SqlDef.PAD_CONTENT_TYPE, null)
+
+		if (!json.get("contentType").isJsonNull) {
+			val contentType = json.get("contentType").getAsString;
+			SqlHelper.insertOrUpdate(connection, SqlDef.PAD, padId, SqlDef.PAD_CONTENT_TYPE, contentType)
+		}
 	}
 }