Worldline's X-GCS-Idempotence-Key is capped at 40 ASCII characters, while a
caller's idempotencyKey is arbitrary. Hashing it to 40 hex characters keeps
the header within bounds while staying deterministic — the same key always
derives the same idempotence key, so a replay dedupes at Worldline.
Worldline's
X-GCS-Idempotence-Keyis capped at 40 ASCII characters, while a caller'sidempotencyKeyis arbitrary. Hashing it to 40 hex characters keeps the header within bounds while staying deterministic — the same key always derives the same idempotence key, so a replay dedupes at Worldline.