* If `only-issue-labels` and `only-pr-labels` are not specified
we limit the listing to `only-labels`.
* If `only-issue-labels` and `only-pr-labels` are specified
but are the same, we limit the listing to these labels.
* If we don't need to make neither issues nor PRs as stale
(`days-before-issue-stale` and `days-before-pr-stale` are
negative) and stale label is the same for issues and PRs
then we filter by this label.