Function parse_ump_signals_for_commitments 

pub fn parse_ump_signals_for_commitments(
    commitments: &CandidateCommitments,
    version: CandidateDescriptorVersion,
    cores_per_para: &TransposedClaimQueue,
    para_id: Id,
    core_index: CoreIndex,
) -> Result<CandidateUMPSignals, CommittedCandidateReceiptError>

Performs the UMP-signal checks and returns the signals.

The check is on the commitments: it needs the claim queue plus the three descriptor fields the core-index check consumes, and nothing else from a receipt. CommittedCandidateReceiptV2::parse_ump_signals is the convenience wrapper for callers that already hold a receipt.