I have a few questions/suggestions but I would like to get some feedback before implementing them. This changeset would rebuild all java, so it would be nice to get this right for the first time.

1. https://issues.guix.info/issue/30730 has a partial fix, icedtea-8 out output is fixed. The same fix could be attempted at icedtea-7, and then we could inherit it.

Also we could get rid of the repeated code in ant-bootstrap and co. 'strip-jar-timestamps the same way Ricardo did this in icedtea-8.

2. ISTM that https://issues.guix.info/issue/31719 is caused by not running strip on the jre directory. I don't know how widespread this kind of issue is throughout the codebase. If it is, then we might need to come up with a more generic solution, but in the meanwhile I would simply add a 'strip-jre-directory phase, or something like that. I guess that should interact with #: strip-binaries though.

3. some javadoc reproducibility issues could be mitigated by tweaking ant build system to pass -notimestamp to javadoc.

WDYT?