RFR: 8343882: BasicAnnoTests doesn't handle multiple annotations at the same position [v2]

[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 two additional commits since the last revision:

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

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Changes:
  - all: https://git.openjdk.org/jdk/pull/21998/files
  - new: https://git.openjdk.org/jdk/pull/21998/files/f410fa14..3f215817

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21998&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21998&range=00-01

  Stats: 187622 lines in 3928 files changed: 61226 ins; 111841 del; 14555 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