During the review of JEP 400, a proposal to provide an overloaded method to `Charset.forName()` was suggested [[1]](https://github.com/openjdk/jdk/pull/4733#discussion_r669693954). This PR is to implement the proposal. A CSR is also drafted as https://bugs.openjdk.java.net/browse/JDK-8275348
------------- Commit messages: - 8270490: Charset.forName() taking fallback default value Changes: https://git.openjdk.java.net/jdk/pull/6045/files Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6045&range=00 Issue: https://bugs.openjdk.java.net/browse/JDK-8270490 Stats: 117 lines in 3 files changed: 115 ins; 0 del; 2 mod Patch: https://git.openjdk.java.net/jdk/pull/6045.diff Fetch: git fetch https://git.openjdk.java.net/jdk pull/6045/head:pull/6045 PR: https://git.openjdk.java.net/jdk/pull/6045
