RFR: 8343622: AesDkCrypto.stringToKey should not return null [v5]

[Weijun Wang]

> When an exception happens inside these stringToKey() methods, it returns a null. This would lead to unexpected NPE some time in the future.

Weijun Wang 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 five additional commits since the last revision:

 - Merge branch 'master' into 8343622
 - update copyright years
 - add cause to exception
 - let it throw NSAE
 - 8343622: AesDkCrypto.stringToKey should not return null

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/21908/files
  - new: https://git.openjdk.org/jdk/pull/21908/files/5d33bf7c..66e814fb

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21908&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21908&range=03-04

  Stats: 492567 lines in 6616 files changed: 259550 ins; 189190 del; 43827 mod
  Patch: https://git.openjdk.org/jdk/pull/21908.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21908/head:pull/21908

PR: https://git.openjdk.org/jdk/pull/21908