[rich7420]

What changes were proposed in this pull request?

S3 Gateway now accepts and verifies SHA512, XXHASH64, XXHASH3 and XXHASH128 trailers through the existing streaming checksum path. Hash4j supplies the three XXHASH algorithms without native binaries; its license notices and the distribution jar list are included.

What is the link to the Apache JIRA

https://issues.apache.org/jira/browse/HDDS-17477

How was this patch tested?

At cf8c064167:

• JDK 21: 497 targeted S3 Gateway unit cases and 14 SDK cases passed across standard and Ratis streaming configurations, including signed and unsigned SHA512 uploads.
• Restoring the two checksum implementation files to the base version caused the 32 new-algorithm endpoint cases to fail with InvalidRequest instead of BadDigest; restoring the fix passed.
• Checkstyle, PMD, license, RAT on a clean source export, and the distribution dependency check passed.
• Fork CI passed: 113 jobs succeeded and 2 were skipped. S3 Gateway reported 2,119 cases and S3 integration reported 391, with no failures, errors or skips.

XXHASH coverage uses independent AWS CRT reference values in stream and endpoint tests. SDK coverage uses SHA512 because XXHASH calculation requires the optional native AWS CRT dependency.

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[rich7420]

Moving this to draft for now. HDDS-17478 moves TrailerHeader into its own class and adds a shared base for both chunk streams, so I'll update this once that's in.