code: private void resetControlID()
      {
          _controlID = null;
          for (Object child : this) {
              if (child instanceof ControlBeanContext)
                  ((ControlBeanContext) child).resetControlID();
          }
      }
docs: Resets the composite control ID for this context and all children beneath it.  This
  can be used to invalidate cached values when necessary (for example, when a context
  is reparented).