ConstReadonlyCANCELLED: "CANCELLED"The backfill was cancelled.
ReadonlyFAILED: "FAILED"The backfill failed.
ReadonlyPENDING: "PENDING"The backfill is pending.
ReadonlyRUNNING: "RUNNING"The backfill is running.
ReadonlySTATE_UNSPECIFIED: "STATE_UNSPECIFIED"The backfill state is unspecified.
ReadonlySUCCEEDED: "SUCCEEDED"The backfill succeeded.
Lifecycle state of a backfill.