RFR: JDK-8297332: Remove easy warnings in base

[Nir Lisker]

On Mon, 21 Nov 2022 11:53:30 GMT, John Hendrikx <jhendrikx at openjdk.org> wrote:

> - Remove unsupported/unnecessary SuppressWarning annotations
> - Remove reduntant type specifications (use diamond operator)
> - Remove unused or duplicate imports
> - Remove unnecessary casts (type is already correct type or can be autoboxed)
> - Remove unnecessary semi-colons (at end of class definitions, or just repeated ones)
> - Remove redundant super interfaces (interface that is already inherited)
> - Remove unused type parameters
> - Remove declared checked exceptions that are never thrown
> - Add missing `@Override` annotations

Marked as reviewed by nlisker (Reviewer).

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PR: https://git.openjdk.org/jfx/pull/957