RFR: 8366522: CodeSource.getCodeSigners() throws NPE within empty certs [v2]

[Kirill Shirokov]

> The new tests cover only NPE scenarios.

Kirill Shirokov 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 two additional commits since the last revision:

 - Merge branch 'master' into JDK-8366522-fix-npe-codeSourceGetCodeSigners
 - 8366522: CodeSource.getCodeSigners() throws NPE within empty certs

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Changes:
  - all: https://git.openjdk.org/jdk/pull/27105/files
  - new: https://git.openjdk.org/jdk/pull/27105/files/237fcdf5..02b96aa4

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27105&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27105&range=00-01

  Stats: 547227 lines in 5474 files changed: 377782 ins; 107549 del; 61896 mod
  Patch: https://git.openjdk.org/jdk/pull/27105.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27105/head:pull/27105

PR: https://git.openjdk.org/jdk/pull/27105