code: @Deprecated
      public void removeRequestHandler(RequestHandler requestHandler) {
          checkMutability();
          requestHandler2s.remove(RequestHandler2.adapt(requestHandler));
      }
docs: Removes a request handler from the list of registered handlers that are run
  as part of a request's lifecycle.
  
  @param requestHandler
  The handler to remove from the current list of request
  handlers.
  @deprecated use {@link AwsClientBuilder#withRequestHandlers(RequestHandler2...)}