RFR: JDK-8309503: Improve javax.lang.model tests for JEP 445 [v2]

[Joe Darcy]

> Improve testing methodology for unnamed classes in javax.lang.model, including coverage of binary names.

Joe Darcy has updated the pull request incrementally with one additional commit since the last revision:

  Improve test to make sure some checking is done.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/14321/files
  - new: https://git.openjdk.org/jdk/pull/14321/files/b142bb8b..5fd8a047

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=14321&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=14321&range=00-01

  Stats: 6 lines in 1 file changed: 6 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/14321.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14321/head:pull/14321

PR: https://git.openjdk.org/jdk/pull/14321