code: public <T> ContextManager execute(Action<T> action, Handler<AsyncResult<T>> resultHandler) {
      vertx.executeBlocking(action, resultHandler);
      return this;
    }
docs: Executes a blocking action on a background thread.
  
  @param action The action to execute.
  @param resultHandler A handler to be called with the action result.
  @return The context manager.