Issue Summary

Sometimes, when a repository on a Bitbucket server is migrated to a destination site, the migration completes as "incomplete," and no errors are logged in the post-migration report to indicate the cause.
The issue arises when the migrated repository has branch permissions restricted to the user given branch permissions not being present in the destination site prior to the datas migration. Note that,

• Bitbucket server allows branch restrictions to reference groups without any permissions for the repo, whereas, in Bitbucket cloud, a group must have at least WRITE permission for the repository to be referenced by a branch restriction.
• Bitbucket Cloud doesn't allow adding users to branch restrictions if they don't have at least WRITE permission

Proposed Suggestion

Preflight checks should be included to validate the repos for missing any permissions for the repo for groups and users. When migrating, users referenced by branch restrictions must have to write permission and migrate branch permissions(restrictions) to a reference group that doesn't have permission.