as per parent bug suggestion:

[~coffeys] Should we also file a related docs issue to add the warning to https://docs.oracle.com/en/java/javase/14/docs/specs/man/jarsigner.html#informational-warnings ?
This may also be a good place to add a link to additional information about POSIX file permissions in case users are wondering what this warning means -- perhaps the POSIX file attributes section of the jdk.zipfs module is the best place: https://download.java.net/java/early_access/jdk15/docs/api/jdk.zipfs/module-summary.html.