OptionalexpectedExpected content version for optimistic concurrency control. When mismatched, mutations are aborted with STALE_TARGET (details.current carries current version). Omitted, no check is made.
Position of the entry to promote; 0 is already the front and is refused.
Parameters for
queue.moveToTop. Move a queued entry to the front so it plays next. Only queue order changes; the relative order of the other entries is kept. Anindexof0, one past the end, and any index while the queue is empty fail withINVALID_INDEX. When the queue cannot be rebuilt the call fails withOPERATION_FAILED, the failure carryingqueueCount.