Fix JDK-8295919 by updating the javadoc to explain that a null or zero-length `digestb` will also result in a short-circuit response
------------- Commit messages: - update copyright year - Fix JDK-8295919 by updating the javadoc to explain that a null or zero-length will also result in a short-circuit response Changes: https://git.openjdk.org/jdk/pull/15933/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15933&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8295919 Stats: 3 lines in 1 file changed: 1 ins; 0 del; 2 mod Patch: https://git.openjdk.org/jdk/pull/15933.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/15933/head:pull/15933 PR: https://git.openjdk.org/jdk/pull/15933
