message: Stream callback may need to return a result (typically if it is a finite stream)
diff: /**
  * @brief Callback type for {{ name.lower_snake_case }}_async.
  */
  -typedef std::function<void({{ return_type.name }})> {{ name.lower_snake_case }}_callback_t;
  +typedef std::function<void({% if has_result %}{{ plugin_name.upper_camel_case }}::Result, {% endif %}{{ return_type.name }})> {{ name.lower_snake_case }}_callback_t;
  /**
  * @brief {{ method_description | replace('\n', '\n *')}}
  