code: public $.Func2<Result, ActionContext, Result> afterHandler(Class<?> controllerClass, Method actionMethod) {
          return DUMB_AFTER_HANDLER;
      }
docs: Returns function that takes {@link Result} and {@link ActionContext} as parameter
  and returns a {@link Result}. This function is called after ActFramework's processing
  has finished.
  <p>
  The afterHandler allows plugin to inject logic to further process the returned result
  or do some updates to `ActionContext` for example to change the response content type
  etc.
  <p>
  The afterHandler shall always returns a result even if there is nothing to do with
  it, it must return the result passed in.
  
  @param controllerClass the controller class
  @param actionMethod    the action method
  @return a logic to be injected before ActFramework handling request