RFR: 8289126: Cleanup unnecessary null comparison before instanceof check in jdk.hotspot.agent

[Chris Plummer]

On Fri, 24 Jun 2022 09:19:33 GMT, Andrey Turbanov <aturbanov at openjdk.org> wrote:

> Update code checks both non-null and instance of a class in jdk.hotspot.agent module classes.
> The checks and explicit casts could also be replaced with pattern matching for the instanceof operator.
> 
> For example, the following code:
> 
>               Object node = tree.getLastSelectedPathComponent();
>               if (node != null && node instanceof SimpleTreeNode) {
>                 showInspector((SimpleTreeNode)node);
>               }
> 
> Can be simplified to:
> 
>               Object node = tree.getLastSelectedPathComponent();
>               if (node instanceof SimpleTreeNode simpleNode) {
>                 showInspector(simpleNode);
>               }
> 
> 
> See similar cleanup in java.base - [JDK-8258422](https://bugs.openjdk.java.net/browse/JDK-8258422)

Marked as reviewed by cjplummer (Reviewer).

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PR: https://git.openjdk.org/jdk/pull/9272