fix: admin console setup page: check JRE version with Runtime.Version

[stokito]

Split from #2563 to simplify of review.

Fixed a bug that I had on 23-ea OpenJDK version. Use Runtime.version() to compare JRE version. It works correctly now.

[stokito]

Yes, but the min jdk was raised to 11 in openfire v4.9 and then to 17 in v5.0

[Fishbowler]

By that measure, why have the check at all?

[stokito]

This is pre-instalation check for the min JDK

[Fishbowler]

So we should make sure it errors gracefully on Java 8?

[stokito]

if the OF was compiled with -source 11 level then the class files may have a new bytecode instructions and when starting on older JRE the java.lang.UnsupportedClassVersionError may occur. It may be need to test if you can get to the page in the JRE8

[guusdk]

That would be interesting: can we get to this page using JRE8? If so, then I believe that we should generate a 'proper' error message, rather than having an UnsupportedClassVersionError or something similar. As Openfire has been using Java 8 for years, I do suspect that a lot of people will still use Java 8 when installing Openfire. Let's give them a clear error condition, rather than a weird stack trace.

What was the original problem with 23-ea? Maybe we can resolve that in a way that doesn't involve using API not available in Java 8?

[akrherz]

This all seems very puzzling to me.

1. I would be surprised that you could to get to the referenced code when invoked from Java 8
2. I sort of agree with Fishbowler and wonder why this check exists at all?
3. Moreover, this check needs to reference something more global in scope than a magic number buried in a JSP

[akrherz]

Anybody wish to champion getting this across the finish line for Openfire 5.0 ?

[stokito]

I guess no one will try to install the Openfire on the JRE8, 9, 10 or at least they'll figure out themselves in a such situation. I had a real bug, not critical, but still. So I think it may be better to merge the PR.

If not, then the simpler fix would be to keep the old version parsing but split also by hyphen - i.e. replace version.split("\\.") with version.split("[-.]+")