RFR: 8367133: DTLS: fragmentation of Finished message results in handshake failure

Mon Sep 15 11:02:37 UTC 2025

The DTLSReassembler may release a Finished message before assembling all necessary fragments.

The newly added test fails without the DTLSReassembler changes, passes with the changes. Other tier1-3 tests continue to pass.

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Commit messages:
 - Clean up comment
 - Extract test to a separate file
 - Wait for all Finished message fragments to arrive
 - Add a test that fragments the Finished message

Changes: https://git.openjdk.org/jdk/pull/27284/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27284&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8367133
  Stats: 78 lines in 2 files changed: 75 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/27284.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27284/head:pull/27284

PR: https://git.openjdk.org/jdk/pull/27284