[jfx20] RFR: 8293587: Fix mistakes in FX API docs [v3]

[John Hendrikx]

On Tue, 7 Feb 2023 19:51:55 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

>> I wish we were using logging...
>
> We aren't very consistent on this. Most of the places where we produce warnings, or where we provide verbose output, are done by printing. At a minimum, those should go to `System.err` rather than `System.out`. Unless there is an API whose expected result is to print something to `System.out`, a library really shouldn't print to System.out (as opposed to a test or a demo app, where it's fine). So the only places I would expect to see it in the library -- meaning source code under `modules/javafx.*/src/main/java/` -- would be in examples in javadoc comments.
> 
> We could file a second follow-up issue (RFE) to consider changing some of our print statements to use logging.

Some investigation is needed if source can ever be null in such cases.  I think some of these are to inform the programmer (not the user) something unexpected happens, in which case it should be an assert or exception.  If it then ever does happen, it should be fixed.

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PR: https://git.openjdk.org/jfx/pull/1025