RFR: JDK-8321484: Make TestImplicitlyDeclaredClasses release independent

[Joe Darcy]

Simple test fix ahead of the fork.

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Commit messages:
 - JDK-8321484: Make TestImplicitlyDeclaredClasses release independent

Changes: https://git.openjdk.org/jdk/pull/17003/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=17003&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8321484
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/17003.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17003/head:pull/17003

PR: https://git.openjdk.org/jdk/pull/17003