OneJar Expand with (or without) sbt-onejar

Question

Is there a way to tell the sbt-onejar SBT plugin to produce a JAR in such way that the .class files of my project are in "expanded" form and not under lib/myproject.jar?

Alternatively, is it possible to tell sbt-onejar to produce a JAR that, when it's loaded, it actually unpacks/expands the nested JARs into a temporary folder and loads them from there, so that things like getResource(...) return paths to physical files as opposed to jar:file:... URLs?

Alternativel, I'd also happy with any vanilla OneJar solutions that help me produce a fat JAR wherein my own .class files would be directly under the fat JAR as opposed to under lib/myproject.jar.

I'm asking because Jetty does not seem to be able to load JSP files from inside of nested JAR files. There does seem to be a workaround by using a custom resource loader (see http://dev.eclipse.org/mhonarc/lists/jetty-users/msg01174.html for a report of the same problem and the workaround) but I don't seem to be able to get my servlets to actually use the overridden getResource method provided in the workaround.

Answer 1

After having read sbt-onejar's source code:

packageOptions in oneJar ++=
  Seq(sbt.Package.ManifestAttributes(
    new java.util.jar.Attributes.Name("One-Jar-Expand") -> "some-file.txt"))

However, I've realized using OneJar with Jetty is quite a problematic beast due to how Jetty loads JSP files—doesn't seem to work with nested JARs—so I'm looking into alternatives now.

EDIT: I've found https://github.com/xerial/sbt-pack and it seems to achieve the same effect as OneJar with the difference of being standard and thus free of problems, much faster, more customizable, and allows defining of convenient custom program entry points.