RFR: 8309667: TLS handshake fails because of ConcurrentModificationException in PKCS12KeyStore.engineGetEntry [v3]

[Weijun Wang]

> The `attributes` field inside the `PKCS12KeyStore.Entry` class might be modified and retrieved at the same time. Make it concurrent.
> 
> The test uses some reflection to get this field and try updating it in multiple threads.

Weijun Wang has updated the pull request incrementally with one additional commit since the last revision:

  more cases to cover

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/14506/files
  - new: https://git.openjdk.org/jdk/pull/14506/files/62b57ba5..dca45ad0

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=14506&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=14506&range=01-02

  Stats: 4 lines in 1 file changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/14506.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14506/head:pull/14506

PR: https://git.openjdk.org/jdk/pull/14506