The jar-in-jar loader does not support multi-release JARs

[ppkarwasz]

To handle multi-release JARs, Java 9 extends the format of jar: URLs:

• if the URL has a #runtime fragment, the JAR file is opened in multi-release mode,
• otherwise the JAR file is opened in mono-release mode.

See, e.g.:

https://github.com/openjdk/jdk/blob/88378ed0584c7eb0849b6fc1e361fd8ea0698caf/src/java.base/share/classes/java/net/JarURLConnection.java#L178-L186

The #runtime fragment is propagated to the URL of the jar file to allow JarUrlConnection to open the file in multi-release mode.

The jar-in-jar loader strips this fragment from rsrc: URLs and therefore breaks multi-release JARs.

Minimal reproducible example

You can find a minimal reproducible example here:

https://github.com/copernik-eu/bug-reproducibility/tree/main/eclipse-jar-in-jar

[iloveeclipse]

Contributions are welcome.