BZ-1192459: quick remediation for deadlock. this should be improved i…

…n order to avoid method level sync.

(definitive solution should be careful in order to preserve clustering sync)

uberfire-widgets/uberfire-widgets-service/uberfire-widgets-service-backend/src/main/java/org/uberfire/ext/services/backend/preferences/UserDataGridPreferencesServiceImpl.java

@@ -43,7 +43,7 @@ public class UserDataGridPreferencesServiceImpl implements UserDataGridPreferenc
     private XStream xs = new XStream();
 
     @Override
-    public void saveGridPreferences( GridPreferencesStore preferences ) {
+    public synchronized void saveGridPreferences( final GridPreferencesStore preferences ) {
         final Path preferencesPath = userServicesBackend.buildPath( identity.getIdentifier(), "datagrid-preferences", preferences.getGlobalPreferences().getKey() );
         try {
             ioServiceConfig.startBatch( preferencesPath.getFileSystem() );