Function group_write_receipt_id 

pub fn group_write_receipt_id(
    endpoint: &str,
    caller_key_id: Option<&str>,
    acc_id: u64,
    idempotency_key: &str,
) -> String

Shared caller+endpoint+account+idempotency identity used by REST preflight, the durable intent ledger and atomic daily-quota receipts.