Extract issues and associated entities for entities outside of the fetched group that belong to an Epic

In GitLab by @iroussos on Jun 14, 2019, 07:21

Currently, we fetch all projects, issues, etc for the specified group when tap-gitlab runs.

With the introduction of Epics, there is a possibility that some issues in an epic reside in a project outside of the group extracted.

An example can be seen by one of the epics in the Meltano Group.

The project some of the issues reside was moved out of the Meltano Group resulting in those issues being referenced by the Epic, but not fetched by tap-gitlab as they are not part of the Group fetched.

We should recursively identify such issues and fetch them and their relevant entities when Epics are extracted.

Start by tracing tap-gitlab's group and Epic extraction entry points and the GitLab API calls they use. Follow how Epic-linked issues are represented, then determine how recursively fetched issues and their associated entities should enter the extraction. Done means issues outside the selected group, such as those linked from an Epic, and their relevant entities are extracted.