git: openjdk/jdk: 8286366: (cs) Charset.put can use putIfAbsent instead of containsKey+put

[Andrey Turbanov]

Changeset: 6b9c1521
Author:    Andrey Turbanov <aturbanov at openjdk.org>
Date:      2022-05-18 17:43:38 +0000
URL:       https://git.openjdk.java.net/jdk/commit/6b9c15211efd0eb35e4ac8edf84c61bb8825a027

8286366: (cs) Charset.put can use putIfAbsent instead of containsKey+put

Reviewed-by: alanb

! src/java.base/share/classes/java/nio/charset/Charset.java