RFR: 8366522: CodeSource.getCodeSigners() throws NPE within empty certs [v3]

[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 three additional commits since the last revision:

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

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/27105/files
  - new: https://git.openjdk.org/jdk/pull/27105/files/02b96aa4..d049213f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27105&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27105&range=01-02

  Stats: 81767 lines in 2479 files changed: 51092 ins; 20172 del; 10503 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