RFR: 8289388: Fix warnings: method is overriding a synchronized method without being synchronized

[Nir Lisker]

On Fri, 8 Jul 2022 19:00:25 GMT, Andy Goryachev <angorya at openjdk.org> wrote:

> Fixes warnings generated by the latest Eclipse: 
> method is overriding a synchronized method without being synchronized

I'm not familiar with the code here, but it should be checked if the overriding method should actually be synchronized. Declaring a method as synchronized is part of its implementation, not its signature, so there can be cases where the overriding method should not be synchronized.

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PR: https://git.openjdk.org/jfx/pull/819