jre8 compatible module about update4j

[spyhunter99]

hmm after looking at the code, a jre8 build would probably be completely different as the code base makes heavy use of jre9 apis

[mordechaim]

This was requested many times in the past, I could do it but would require lots of work. Instead of maintaining 2 releases I could make use of a Multi-Release module. I can leave this issue open for a while, let's see how I will proceed.

[mordechaim]

I finally tracked down every single incompatibility and implemented JDK 8 compatible classes.

But since we need special handling with the module system it cannot be completed without a Multi-Release jar. Here's where the tricky part begins, there is no out-of-the-box Maven support. I tried following a few suggestions from here but could not get it to work cleanly. Additionally, it get's really challenging to maintain the codebase.

One other solution would be to use source 8 and target 9, this would set the class version to 52 (jdk8) and still allow using classes in jdk9. But then I have to run code in an if/else block and check for versioning. Cleaner, indeed.

[mordechaim]

For now, this will not be implemented.