`Hashtable` doesn't allow `null` values. It means we can replace containsKey+get with get+null check. It's clearer and a bit faster.
------------- Commit messages: - [PATCH] Avoid redundant Hashtable.containsKey call in CodeSource.readObject Changes: https://git.openjdk.org/jdk/pull/21753/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21753&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8343194 Stats: 6 lines in 1 file changed: 0 ins; 3 del; 3 mod Patch: https://git.openjdk.org/jdk/pull/21753.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/21753/head:pull/21753 PR: https://git.openjdk.org/jdk/pull/21753
