code: public void popListener(Class<? extends ChainingListener> listenerClass)
      {
          if (StackableChainingListener.class.isAssignableFrom(listenerClass)) {
              this.listeners.get(listenerClass).pop();
          }
      }
docs: Remove the last instance corresponding to the passed listener class if it's stackable, in order to go back to the
  previous state.
  
  @param listenerClass the class of the chaining listener to pop