From Bitbucket 4.8 there is a feature that allows you to assign default reviewers for pull requests: BSERV-2924. These features can work alongside each other without interfering with each other, with one notable caveat. If you add default reviewers using the Bitbucket feature and set a certain number of them to be required, then reviewers added using the ScriptRunner event handler will not be able to approve or reject a pull request until one of the Bitbucket reviewers has weighed in. This is consistent with how Bitbucket Server’s default reviewers feature normally behaves. In short, the reviewers that are required to weigh in by Bitbucket Server settings will have the first say on a pull request.