RFR: 8289616: Drop use of Thread.stop in AppContext

[Iris Clark]

On Fri, 12 Aug 2022 20:14:27 GMT, Phil Race <prr at openjdk.org> wrote:

> Thread.stop() and ThreadGroup.destroy() are called by sun.awt.AppContext.dispose()
> 
> These should no longer be called. Both are deprecated for removal.
> ThreadGroup.destroy() does nothing. Thread.stop() throws UnsupportedOperationException
> for virtual threads, and is expected to do so for all threads if it is not removed before then.
> 
> This fix stops calling these methods and prints a warning from dispose() to encourage
> callers to move away from AppContext which itself will likely be removed in a future release
> since the Webstart and Plugin scenarios that needed it are no longer supported.
> Although most tests that use AppContext are now irrelevant only one test actually fails
> and is removed  so we are doing the least here and the big job of completely getting rid of
> AppContext is for another day.

src/java.desktop/share/classes/sun/awt/AppContext.java line 406:

> 404:             Remove all uses of this internal class as soon as possible.
> 405:             There is no replacement.
> 406:             """);

Should some portion of this warning be included in an `@implNote` in this method's JavaDoc?

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PR: https://git.openjdk.org/jdk/pull/9863