code: private void initListeners()
    {
      ClassLoader parent = getParent();
  
      for (; parent != null; parent = parent.getParent()) {
        if (parent instanceof EnvironmentClassLoader) {
          EnvironmentClassLoader loader = (EnvironmentClassLoader) parent;
  
          if (_stopListener == null)
            _stopListener = new WeakStopListener(this);
  
          loader.addListener(_stopListener);
  
          return;
        }
      }
    }
docs: Adds self as a listener.