code: protected Stack<Component> getComponentStack() {
      @SuppressWarnings("unchecked")
      Stack<Component> componentStack = (Stack<Component>) stack.getContext().get(COMPONENT_STACK);
      if (componentStack == null) {
        componentStack = new Stack<Component>();
        stack.getContext().put(COMPONENT_STACK, componentStack);
      }
      return componentStack;
    }
docs: Gets the component stack of this component.
  
  @return the component stack of this component, never <tt>null</tt>.