Why sortByProfitabilityUsingMaxCover is using maxCover ?

[mitmotw]

prysm/beacon-chain/rpc/prysm/v1alpha1/validator/proposer_attestations.go

Line 148 in a85b444

selectedKeys, _, err := aggregation.MaxCover(candidates, len(candidates), true /* allowOverlaps */)

sortByProfitabilityUsingMaxCover is doing maxCover for the attestations from same slot.
However I guess there might be some attestations from different committee index.
The test codes are not caring about attestations from different committee as well

The whole attestations are guaranteed to be from same committee ?

The proposer is fetching those attestations from the pools,
so I'm not getting how it's guaranteed.

prysm/beacon-chain/rpc/prysm/v1alpha1/validator/proposer_attestations.go

Line 28 in a85b444

atts := vs.AttPool.AggregatedAttestations()

Please fix me if I'm wrong. 🙏