Optional ReadonlycoordinatorKeys to look up coordinators for (v4+, batched lookup).
If provided, key is ignored.
ReadonlykeyThe coordinator key (group ID or transactional ID). Used in v0–v3. In v4+ this is ignored if coordinatorKeys is provided.
Optional ReadonlykeyThe coordinator type (v1+).
Optional ReadonlytaggedTagged fields (v4+).
FindCoordinator request payload.