Add null pointer guard in test formatter (since it can be called with a log record without parameters).
------------- Commit messages: - Adding null check for test formatter. Changes: https://git.openjdk.org/jdk/pull/24619/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24619&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8354513 Stats: 6 lines in 1 file changed: 4 ins; 0 del; 2 mod Patch: https://git.openjdk.org/jdk/pull/24619.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/24619/head:pull/24619 PR: https://git.openjdk.org/jdk/pull/24619
