[shivanee-p]

Add resolveResponsePayload to errorUtil so LoggerHelper can populate response.payload with the full response serialized as JSON (string payloads are returned as-is). It prefers the raw response gax provides for paginated and long-running calls over the processed response, and returns undefined when there is no response.

[gemini-code-assist]

Code Review

This pull request introduces the resolveResponsePayload function to serialize response payloads as JSON (or return them as-is if they are already strings), preferring the raw response when available. Unit tests were also added to verify its behavior. The reviewer suggested improving the handling of Uint8Array or Buffer payloads by decoding them to a UTF-8 string first, preventing inefficient serialization and unreadable logs.

[quirogas]

LGTM! Approved with 2 minor non-blocking nits so this PR is unblocked.

[quirogas]

Nit: Now that safeJsonStringify (lines 840-850) automatically base64-encodes Buffer, Uint8Array, and ArrayBuffer values in its replacer, isBuffer (line 778) and the 20-line cleanMap Buffer-encoding loop in resolveServerExceptionDetails in the same file are redundant; resolveServerExceptionDetails can pass map directly to safeJsonStringify(map).

[quirogas]

Nit: Consider removing the unused rawResponse?: unknown parameter on resolveResponsePayload (response.payload is an L4 error-only attribute in the Milestone 2 Design Doc and never receives paginated/LRO rawResponse), avoiding allocating intermediate Uint8Array and Buffer views in toBytes / encodeBase64 when value is already a Buffer or Uint8Array, and checking Array.isArray((val as {data?: unknown}).data) alongside (val as {type?: unknown}).type === 'Buffer' in safeJsonStringify (line 844) before re-reading this[key].