RFR: 8287696: Avoid redundant Hashtable.containsKey call in JarVerifier.doneWithMeta

[Andrey Turbanov]

On Sat, 28 May 2022 12:00:00 GMT, Andrey Turbanov <aturbanov at openjdk.org> wrote:

> Hashtable doesn't allow `null` values. So, instead of pair `containsKey`/`remove` calls, we can directly call `remove` and then compare result with `null`.
> https://github.com/openjdk/jdk/blob/2c461acfebd28fe5ef62805cbb004f91a3b18f08/src/java.base/share/classes/java/util/jar/JarVerifier.java#L433-L436

Thank you for review!

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PR: https://git.openjdk.org/jdk/pull/8935