JDK 19+21 early-access build is reproducible

[John Neffenger]

Starting yesterday, for the first time, the JDK can create reproducible 
builds of the JDK!

Pull request 8478 [1] was the last reproducibility bug remaining in my 
JDK builds on Linux, and it's included in the latest JDK 19+21 
early-access build. [2] OpenJDK 19 will be generally available on 
September 20, 2022.

That also means there's nothing in the JDK that's holding back any Java 
application from having reproducible builds. The link below lists all 
the "reproducible build" fixes for OpenJDK:

https://bugs.openjdk.java.net/issues/?jql=labels+%3D+reproducible-build

I tested on six Linux architectures (amd64, arm64, armhf, i386, ppc64el, 
s390x), and the entire JDK is reproducible including the command-line 
tools, demos, API documentation, JMOD archives, native libraries, and 
man pages -- even when using a different build path. Note that I didn't 
test on macOS or Windows.

A big thank you to Magnus Ihse Bursie and Andrew Leonard for doing much 
of the work to make this possible.

John

[1]: https://github.com/openjdk/jdk/pull/8478
[2]: https://jdk.java.net/19/