onejars under Jigsaw

[org.openjdk at io7m.com]

Hello!

When I write command line applications, I typically produce an
additional platform-independent "onejar" for convenience. More
specifically, I use the Maven Shade plugin to pack all of the classes
of all of the dependencies into a single jar with MainClass attribute.
The main benefit of doing things this way is that the jar file remains
platform independent (assuming that the code itself is platform
independent). A good example of this is my kstructural package:

  http://io7m.github.io/kstructural/

The main command-line jar program is an amalgamation of all of the
other modules and all dependencies:

  https://repo1.maven.org/maven2//com/io7m/kstructural/io7m-kstructural-cmdline/0.3.0/io7m-kstructural-cmdline-0.3.0-main.jar

Is there already a facility to do this under Jigsaw? Jlink is not quite
what I'm looking for in this case, because the produced artifacts would
be platform-specific.

Clearly, producing onejars in pre-Jigsaw Java is like taking all of the
problems of the classpath and smashing them into one unfixable lump for
deployment. The fact that we often get builds that appear to work using
this method seems to owe a lot to blind luck.

No doubt doing this sort of transformation is a hell of a lot safer when
there are module boundaries to work with, services declared in module
descriptors, and so on.

I suspect I could address the same question to the Maven Shade list,
but I thought I'd better check here first. :)

M