private void enableMaintenanceMode(){
synchronized (maintenanceEnabled) {
    if (!maintenanceEnabled.getAndSet(true)) {
      maintenanceFilter.enableMaintenanceMode();
    }
  }
}

private void enableMaintenanceMode ( ) { synchronized ( maintenanceEnabled ) { if ( ! maintenanceEnabled . getAndSet ( true ) ) { maintenanceFilter . enableMaintenanceMode ( ) ; } } }
enables maintenance mode by enabling the maintenance filter to disable modification by certain endpoints .
