RFR: 8346300: Add @Test annotation to a test method

[Naoto Sato]

A very minor test fix.

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Commit messages:
 - added @Test

Changes: https://git.openjdk.org/jdk/pull/22773/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22773&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8346300
  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/22773.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22773/head:pull/22773

PR: https://git.openjdk.org/jdk/pull/22773