Function commit_outcome 

pub fn commit_outcome(
    offsets: &GroupOffsets,
    result: Result<Vec<ConsumerGroupOffsetOutcome>, AdminError>,
) -> Result<usize, BackupError>

How many offsets one group’s commit put back, or why it put back none.

The admin client retries COORDINATOR_LOAD_IN_PROGRESS, COORDINATOR_NOT_AVAILABLE, NOT_COORDINATOR and REBALANCE_IN_PROGRESS until Kafka’s default.api.timeout.ms runs out, so a timeout means the group’s coordinator never became ready, not that the cluster refused.

Errors

BackupError::Cluster when the call failed or timed out, or when the coordinator refused any partition.