Initially, the fix was proposed here:
https://mail.openjdk.java.net/pipermail/swing-dev/2019-October/009846.html
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Dear Swing maintainers,

I was referred to this mailing list from build-dev. I would like to fix the compiler warnings caused by the Swing demo code. Please find original posting below.

As I learned that attachments might be stripped please find my patches also in this gist: https://gist.github.com/marchof/59923f8e2ebab0768ed76ffb5315a2c7

Best regards,
-marc



MOTIVATION

As a developer of the JaCoCo code coverage library I do lots of JDK builds. JDK
builds are simple, fast and produce minimal log output. Nice! What annoys me
though are plenty of compiler warnings at the end of the build caused by the
example code in src/demo/share/jfc

FIX

I propose a series of 3 patches (based on each other) which fixes all compiler
warnings for the demos:

patch1.txt - Fix compiler warnings in demos: raw types
patch2.txt - Fix compiler warnings in demos: deprecated APIs
patch3.txt - Fix compiler warnings in demos: deprecated Applet APIs

While patch 1 & 2 do not change functionality patch 3 actually removes the
Applet versions of some of the demos. The java main versions of the same demos are still intact.