Function commit_checks 

pub async fn commit_checks(
    endpoint: &Endpoint,
    tracker: &CommitTracker,
    fault: &str,
    acknowledged: &BTreeMap<i32, i64>,
) -> Vec<CommitCheck>

One CommitCheck per partition of acknowledged: the last commit the coordinator acknowledged before fault, against what OffsetFetch returns now and the partition’s log end.

A group that had acknowledged no commit yet is checked on every one of its partitions from zero, so each fault is checked for each group and a group that never commits is a finding rather than an absence.