JDK's java.desktop module has internal code that interoperates with multiple versions of the GTK platform library.
This is primarily to support the Swing GTK LookAndFeel.

The JDK previously included support for interoperating with the GTK 2 version of the library, which is reaching the end of its life.
GTK 3 long ago superseded it and is supported by JDK as the preferred default, in which case to use GTK 2, apps must request it using the `jdk.gtk.version` system property.
And since many recent distros make GTK 2 only an optional install, it may require extra work to use it, and future distros will likely not provide any way to install it.

Since all versions of Linux to be supported by JDK 24 provide GTK3, it is time to remove the GTK2 support in JDK.

Setting the `jdk.gtk.version` property to `2` or `2.2` will no longer have any effect, GTK 3 will be loaded.