JstlTest failure with JDK 9

[sbordet]

@janbartel, can you please review JstlTest when using JDK 9 to run the tests ? It fails with:

org.apache.jasper.JasperException: The absolute uri: http://java.sun.com/jsp/jstl/core cannot be resolved in either web.xml or the jar files deployed with this application

I have currently "disabled" the test for JDK 9 only using JUnit's Assume. Feel free to remove it when the test works with JDK 9 as well

[janbartel]

The test will need to remain disabled in jetty-9.

The problem is that with jdk-9, the system classloader is not a URLClassLoader and thus cannot be interrogated for its urls. This is a technique that our o.e.j.webapp.WebInfConfiguration class uses to find the urls of jars on the server's classpath, and apply user-defined patterns that control the ordering/inclusions of jars to scan for tags, resources, web-fragment.xmls and annotations.

This works fine with jdk-9 for the jetty-maven plugin because maven's ClassRealm classloader is a URLClassLoader. The distribution also works fine with jdk-9 because start.jar creates its own URLClassloader to be the parent of the webapp.

However it will fail on probably almost every embedded environment.

This will need some thought to fix, and probably help from jdk-9 apis, so won't be possible to fix in jetty-9.

[gregw]

I'm guessing it will also fail if start.jar runs in exec mode, as it will not have the URLClassloader.

So with java9, we cannot scan any jars that are on the system classpath? Hmmm we may need to reconsider our basic class loading and start mechanism more than we'd thought :(

[janbartel]

Re-established the JstTest after fixing issue #1933