Apple no longer supports this platform. There is no reason to target it for new releases. Java is not abandoning MacOS.

It's only Java on macOS for x64 that gets dropped. Java on Apple's M-type CPUs will still be alive and kicking.

It is open source, anyone is free to send patches, given that OpenJDK is like Linux distros.

Write once, run everywhere refers to the target bytecode running on a compliant JVM. Since apple itself has mentioned to officially drop intel support, OpenJDK maintainers have no reason to continue support on a deprecated hardware. That said, if there is any enterprise/ community that requires a port for intel macs then, they can maintain it. link to become a maintainer: https://openjdk.org/projects/

"a Win10 machine for testing on my left hand side here..."

Well, the Latin word for "left" is "sinister", so that tracks.