RFR: 8270490: Charset.forName() taking fallback default value [v3]

[Sergey Bylokhov]

On Fri, 22 Oct 2021 17:33:43 GMT, Naoto Sato <naoto at openjdk.org> wrote:

>> 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
>
> Naoto Sato has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Removed `@throws IllegalCharsetNameException`

Just an idea, should we check that the second parameter is null or not? Any pros and cons of that?
For example should this code be allowed:

var cs = Charset.forName(charsetName, null);
if (cs == null) {
   System.err.println("Used UTF-8 encoding instead of "+charsetName+");
   cs = StandardCharsets.UTF_8;
}

Or something like this should be forced:

var cs = Charset.forName(charsetName, fallback);
if (cs == fallback) {
   System.err.println("Used UTF-8 encoding instead of "+charsetName+");
}

I have no preference.

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PR: https://git.openjdk.java.net/jdk/pull/6045