RFR: JDK-8262509: JSSE Server should check the legacy version in TLSv1.3 ClientHello

[John Jiang]

Per RFC 8446, section 4.1.2, the legacy_version field in ClientHello message MUST be set to 0x0303 (TLSv1.2).
T13ClientHelloConsumer should do this check like that T13ServerHelloConsumer does.

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Commit messages:
 - JDK-8262509: JSSE Server should check the legacy version in TLSv1.3 ClientHello

Changes: https://git.openjdk.java.net/jdk/pull/2772/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2772&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8262509
  Stats: 5 lines in 1 file changed: 5 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2772.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2772/head:pull/2772

PR: https://git.openjdk.java.net/jdk/pull/2772