Reports whether a plugin carrying this name is pending.

A pure read — it neither resolves nor constructs anything. It exists so a caller applying several exclusions can validate the whole set BEFORE removing any of them: unregister mutates immediately, so removing as you go leaves earlier exclusions applied when a later name turns out to be misspelled, handing a caller that catches the error a silently altered application.

Answers against the registered plugin list, which startup does NOT clear — so after start() it still reports true for a plugin that has already run. Its purpose is pre-start() validation, and unregister throws once any plugin has registered, so a later answer is not actionable either way.