Support trailing checksum in DefaultAwsV4HttpSigner

[dagnir]

Motivation and Context

This commit moves the support for trailing checksums from HttpChecksumStage to the V4 signer signer implementation; this puts it in line with how sync chunked bodies are already handled.

Modifications

Testing

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Checklist

• I have read the CONTRIBUTING document
• Local run of mvn install succeeds
• My code follows the code style of this project
• My change requires a change to the Javadoc documentation
• I have updated the Javadoc documentation accordingly
• I have added tests to cover my changes
• All new and existing tests passed
• I have added a changelog entry. Adding a new entry must be accomplished by running the scripts/new-change script and following the instructions. Commit the new file created by the script in .changes/next-release with your changes.
• My change is to implement 1.11 parity feature and I have updated LaunchChangelog

License

• I confirm that this pull request can be released under the Apache 2 license

[Copilot]

Pull Request Overview

This PR moves trailing checksum support from HttpChecksumStage to the V4 signer implementation to align with how sync chunked bodies are handled. The change consolidates checksum handling logic within the signer rather than having it split between different pipeline stages.

• Removes trailing checksum logic from HttpChecksumStage for async operations
• Implements comprehensive async chunked encoding support in AwsChunkedV4PayloadSigner
• Adds new subscriber classes for reactive stream checksum calculation

Reviewed Changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
HttpChecksumStage.java	Removes async trailing checksum logic that was handled separately
DefaultAwsV4HttpSigner.java	Updates async signing flow to support chunked encoding with checksums
AwsChunkedV4PayloadSigner.java	Implements async chunked encoding with trailing checksum support
V4PayloadSigner.java	Adds async beforeSigning hook for payload preprocessing
SignerUtils.java	Adds async content length calculation utilities
LengthCalculatingSubscriber.java	New subscriber for calculating content length from reactive streams
UnbufferedChecksumSubscriber.java	New subscriber for checksum computation without buffering
ChunkedEncodedPublisher.java	Minor improvements to trailer handling and adds getter methods
Various test files	TCK compliance tests and unit tests for new subscriber classes

Comments suppressed due to low confidence (1)

core/http-auth-aws/src/main/java/software/amazon/awssdk/http/auth/aws/internal/signer/AwsChunkedV4PayloadSigner.java:190

• [nitpick] This error message is split across lines making it harder to read. Consider consolidating it into a single, well-formatted message.

                                                          // should not happen, this header is added by moveContentLength

[Copilot]

The error message should be more descriptive and use a more specific exception type. Consider using IllegalStateException instead of RuntimeException and improve the message clarity.

Suggested change

	// should not happen, this header is added by moveContentLength
	.orElseThrow(() -> new RuntimeException("x-amz-decoded-content-length "
	+ "header not present"));
	// This header is expected to be added by moveContentLength. Its absence indicates an unexpected state.
	.orElseThrow(() -> new IllegalStateException("Missing required header: x-amz-decoded-content-length. "
	+ "This header is necessary for calculating the encoded content length."));

[Copilot]

The variable 'request' is being passed to calculateEncodedContentLength, but it should be 'requestBuilder' which is the actual SdkHttpRequest.Builder instance being used in this context.

Suggested change

	long encodedContentLength = calculateEncodedContentLength(request, decodedContentLength);
	long encodedContentLength = calculateEncodedContentLength(requestBuilder, decodedContentLength);

[Copilot]

The variable 'request' should be 'requestBuilder' to maintain consistency with the rest of the method and ensure the header is added to the correct request builder instance.

Suggested change

	request.appendHeader(X_AMZ_TRAILER, checksumHeaderName);
	requestBuilder.appendHeader(X_AMZ_TRAILER, checksumHeaderName);

[Copilot]

The variable 'request' should be 'requestBuilder' to maintain consistency and ensure the header is set on the correct request builder instance.

Suggested change

	request.putHeader(Header.CONTENT_LENGTH, Long.toString(encodedContentLength));
	requestBuilder.putHeader(Header.CONTENT_LENGTH, Long.toString(encodedContentLength));

[Copilot]

The variable 'request' should be 'requestBuilder' to maintain consistency and ensure the header is appended to the correct request builder instance.

Suggested change

	request.putHeader(Header.CONTENT_LENGTH, Long.toString(encodedContentLength));
	request.appendHeader(CONTENT_ENCODING, AWS_CHUNKED);
	requestBuilder.putHeader(Header.CONTENT_LENGTH, Long.toString(encodedContentLength));
	requestBuilder.appendHeader(CONTENT_ENCODING, AWS_CHUNKED);

[dagnir]

Closing to break this up into smaller PRs. Addition of truncating content length from upstream publisher adds too much to this PR.

• Truncate to content in chunked publisher #6304

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