RFR: 8351232: NPE: Cannot invoke "getDeclarationAttributes" because "sym" is null

[Adam Sotona]

Javac throws NPE in very specific circumstances described in [JDK-8351232](https://bugs.openjdk.org/browse/JDK-8351232).
The NPE has been fixed as a side effect of "stripMetadata" call in the recent [JDK-8355065](https://bugs.openjdk.org/browse/JDK-8355065) fix.

This PR only adds a test case to avoid regression of the NPE.

Please review.

Thank you,
Adam

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Commit messages:
 - NPE: Cannot invoke "getDeclarationAttributes" because "sym" is null

Changes: https://git.openjdk.org/jdk/pull/25098/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25098&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8351232
  Stats: 142 lines in 6 files changed: 134 ins; 3 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/25098.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25098/head:pull/25098

PR: https://git.openjdk.org/jdk/pull/25098