code: public static void registerSubordinateControl(final String controlId) {
  		UIContext uic = UIContextHolder.getCurrentPrimaryUIContext();
  		if (uic == null) {
  			throw new SystemException("No User Context available to register Subordinate Control.");
  		}
  		Set<String> controls = (Set<String>) uic.getFwkAttribute(SUBORDINATE_CONTROL_SESSION_KEY);
  		if (controls == null) {
  			controls = new HashSet<>();
  			uic.setFwkAttribute(SUBORDINATE_CONTROL_SESSION_KEY, controls);
  		}
  		controls.add(controlId);
  	}
docs: Register the Subordinate Control so that it can be applied by the {@link SubordinateControlInterceptor}.
  
  @param controlId the subordinate id