Adjust the leading javadoc sentence of several collections mutator methods to include "(optional operation)" as appropriate. Also adjust doc for UnsupportedOperationException on those methods as necessary.
------------- Commit messages: - Adjust wording of various UnsupportedOperationException docs. - Note (optional operation) and UOE in appropriate places. Changes: https://git.openjdk.org/jdk/pull/15127/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15127&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8159527 Stats: 70 lines in 5 files changed: 17 ins; 8 del; 45 mod Patch: https://git.openjdk.org/jdk/pull/15127.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/15127/head:pull/15127 PR: https://git.openjdk.org/jdk/pull/15127
