RFR: 8343882: BasicAnnoTests doesn't handle multiple annotations at the same position [v3]

[Liam Miller-Cushon]

> Please consider this fix to `test/langtools/tools/javac/processing/model/type/BasicAnnoTests.java`. Due to a long-standing bug in the test, some test cases were not being processed if there were multiple assertions for annotations at the same position. All existing cases in the test still pass after this fix.

Liam Miller-Cushon 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 remote-tracking branch 'origin/master' into JDK-8343882
 - Merge remote-tracking branch 'origin/master' into JDK-8343882
 - 8343882: BasicAnnoTests doesn't handle multiple annotations at the same position

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/21998/files
  - new: https://git.openjdk.org/jdk/pull/21998/files/3f215817..38b27e05

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21998&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21998&range=01-02

  Stats: 154903 lines in 4708 files changed: 110875 ins; 29228 del; 14800 mod
  Patch: https://git.openjdk.org/jdk/pull/21998.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21998/head:pull/21998

PR: https://git.openjdk.org/jdk/pull/21998