code: private void assertInitialized() {
  
  		if (!services.isShuttingDown() && !services.isShutdownDone()) {
  
  			// wait for service layer to be initialized
  			while (!services.isInitialized()) {
  
  				try { Thread.sleep(1000); } catch (Throwable t) {}
  			}
  		}
  	}
docs: ----- private methods -----