Support for resolving S3-backed payloads in SNS non-raw messages (Fixes #175)

[danielferraz-git]

Description

When SNS is configured to deliver messages to SQS without RawMessageDelivery enabled, it wraps the message body in a JSON envelope. This currently prevents the SQS Extended Client from resolving large payloads, as it expects the SQS message body itself to be the S3 pointer.

This PR introduces an opt-in feature to support SNS-wrapped messages. It allows the client to identify S3 pointers within the SNS "Message" field, resolve the actual payload from S3, and update the JSON envelope in-place. This ensures that all other SNS metadata (e.g., Subject, Type, MessageId, Timestamp) is preserved for the consumer.

Key Changes

• New Configuration: Added payloadSupportFromSnsEnabled to both ExtendedClientConfiguration and ExtendedAsyncClientConfiguration. This feature is disabled by default to maintain backward compatibility.
• Robust JSON Resolution: Utilized Jackson (ObjectMapper) to perform structural updates to the SNS JSON body. This ensures proper character escaping and structural integrity when replacing the S3 pointer with the resolved content.
• Preservation of Metadata: Unlike simple unwrapping, this implementation preserves the entire SNS envelope, updating only the "Message" field while keeping other attributes like Subject intact.
• Sync & Async Support: Enhanced AmazonSQSExtendedClient and AmazonSQSExtendedAsyncClient to handle recursive payload resolution within JSON-formatted message bodies.
• Testing: Added a comprehensive test suite (AmazonSQSExtendedClientSnsTest and AmazonSQSExtendedClientUtilTest) covering:
  • Successful resolution of large payloads inside SNS envelopes.
  • Preservation of non-message fields in the envelope.
  • Standard SQS message compatibility when the SNS flag is enabled.
  • Graceful handling of malformed or non-SNS JSON bodies.

Related Issue
Fixes #175