[jdk17u-dev] RFR: 8297878: KEM: Implementation

[Weijun Wang]

This is the backport of the KEM API. The change is identical to https://github.com/openjdk/jdk17u-ri/commit/e9d2641a14407380264b50fa2fe299980fe5f214.

@gnu-andrew, please take a review. Thanks.

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Commit messages:
 - Backport e9d2641a14407380264b50fa2fe299980fe5f214

Changes: https://git.openjdk.org/jdk17u-dev/pull/2518/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2518&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8297878
  Stats: 1782 lines in 9 files changed: 1768 ins; 3 del; 11 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/2518.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/2518/head:pull/2518

PR: https://git.openjdk.org/jdk17u-dev/pull/2518