Bug 1526

PLarsson reported incompatibility using jogamp's fat jar wrapped in an exe by launch4j.
See https://forum.jogamp.org/No-Jar-name-in-Errors-tp4028798p4043856.html

This code...
```
if(0 >= ssp.lastIndexOf(".jar")) {
    throw new IllegalArgumentException("No Jar name in <"+classJarUri+">");
}
```
... checks that the archive file name contains ".jar", not that it actually ends in ".jar". This has the interesting side effect that if I just rename my ReallyAwesomeProgram.exe to f.ex. ReallyAwe.jarsomeProgram.exe, everything suddenly works!

So... my usecase technically works, but is hindered by this file name check, which is incorrect so I can bypass it in ugly ways.