I'm one of the maintainers of the GitLab plugin (
https://github.com/jenkinsci/gitlab-plugin). It has recently undergone a major rewrite, and a group of us are continuing to actively develop it, having taken over from the original author. The GitLab MR Builder plugin is not actively maintained; the author is only merging patches if they are submitted by users. So I would humbly suggest that you switch to our plugin. It has all the features of the other one, plus an active support community. If you have trouble getting started with it, you can chat to us on IRC in #gitlab-plugin on the Freenode network, or open an issue in the GitHub project if you think you have found a bug (but the current version is stable for most use cases).