RFR: 8294983: SSLEngine throws ClassCastException during handshake [v2]

[Kevin Driver]

> Fixes a scenario where a `ServerHandshakeContext` might be cast as a `ClientHandshakeContext`.

Kevin Driver has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:

 - updated copyright
 - Merge branch 'master' of github.com:openjdk/jdk into JDK-8294983
 - set consumer to null if we're not in client mode

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Changes:
  - all: https://git.openjdk.org/jdk/pull/13727/files
  - new: https://git.openjdk.org/jdk/pull/13727/files/ca4e3ee1..a249a9bb

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13727&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13727&range=00-01

  Stats: 4160 lines in 34 files changed: 2947 ins; 22 del; 1191 mod
  Patch: https://git.openjdk.org/jdk/pull/13727.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13727/head:pull/13727

PR: https://git.openjdk.org/jdk/pull/13727