Remove unused class `KeyBuilder` and unused field `unusedSets`. Update a comment which used javadoc syntax. Mark `KeyEnumeration` and `FontKey` classes as *`final`*.
All the client tests are green. ------------- Commit messages: - 8329761: Remove unused KeyBuilder and unusedSets from StyleContext Changes: https://git.openjdk.org/jdk/pull/18659/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18659&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8329761 Stats: 156 lines in 1 file changed: 0 ins; 150 del; 6 mod Patch: https://git.openjdk.org/jdk/pull/18659.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/18659/head:pull/18659 PR: https://git.openjdk.org/jdk/pull/18659
