jar for libGDX JRuby game crashes

[jrab89]

I'm trying to package a minimal libGDX game written in JRuby with Warbler. The game works when run from the command-line, but when I run the jar built by Warbler, it crashes. Here's the source for this minimal game: https://github.com/jrab89/hello_libgdx_jruby

Here's how to run the game from the command-line (results in a graphical window that says "hello libgdx!"):

$ git clone git@github.com:jrab89/hello_libgdx_jruby.git
Cloning into 'hello_libgdx_jruby'...
remote: Enumerating objects: 10, done.
remote: Counting objects: 100% (10/10), done.
remote: Compressing objects: 100% (7/7), done.
remote: Total 10 (delta 0), reused 10 (delta 0), pack-reused 0
Receiving objects: 100% (10/10), done.
$ cd hello_libgdx_jruby
$ ruby -v
jruby 9.2.14.0 (2.5.7) 2020-12-08 ebe64bafb9 Java HotSpot(TM) 64-Bit Server VM 25.172-b11 on 1.8.0_172-b11 +jit [darwin-x86_64]
$ bundle install
Using rake 13.0.3
Using ast 2.4.2
Using thread_safe 0.3.6 (java)
Using descendants_tracker 0.0.4
Using ice_nine 0.11.2
Using axiom-types 0.1.1
Using bundler 1.17.3
Using coderay 1.1.3
Using coercible 1.0.0
Using diff-lcs 1.4.4
Using equalizer 0.0.11
Using ffi 1.14.2 (java)
Using jar-dependencies 0.4.1
Using virtus 1.0.5
Using maven-tools 1.1.6
Using ruby-maven-libs 3.3.9
Using ruby-maven 3.3.12
Using jbundler 0.9.3
Using jruby-jars 9.2.14.0
Using jruby-rack 1.1.21
Using method_source 1.0.0
Using parallel 1.20.1
Using parser 3.0.0.0
Using spoon 0.0.6
Using pry 0.13.1 (java)
Using rainbow 3.0.0
Using regexp_parser 2.0.3
Using rexml 3.2.4
Using rspec-support 3.10.2
Using rspec-core 3.10.1
Using rspec-expectations 3.10.1
Using rspec-mocks 3.10.2
Using rspec 3.10.0
Using rubocop-ast 1.4.1
Using ruby-progressbar 1.11.0
Using unicode-display_width 2.0.0
Using rubocop 1.9.1
Using rubyzip 1.3.0
Using warbler 2.0.5
Bundle complete! 5 Gemfile dependencies, 39 gems now installed.
Use `bundle info [gemname]` to see where a bundled gem is installed.
$ jbundle
...

jbundler provided classpath:
----------------

jbundler runtime classpath:
---------------------------
/Users/jeff.rabovsky/.m2/repository/net/java/jinput/jinput/2.0.5/jinput-2.0.5.jar
/Users/jeff.rabovsky/.m2/repository/org/yaml/snakeyaml/1.26/snakeyaml-1.26.jar
/Users/jeff.rabovsky/.m2/repository/com/badlogicgames/gdx/gdx-platform/1.9.14/gdx-platform-1.9.14-natives-desktop.jar
/Users/jeff.rabovsky/.m2/repository/org/lwjgl/lwjgl/lwjgl_util/2.9.3/lwjgl_util-2.9.3.jar
/Users/jeff.rabovsky/.m2/repository/com/badlogicgames/jlayer/jlayer/1.0.1-gdx/jlayer-1.0.1-gdx.jar
/Users/jeff.rabovsky/.m2/repository/org/lwjgl/lwjgl/lwjgl-platform/2.9.3/lwjgl-platform-2.9.3-natives-linux.jar
/Users/jeff.rabovsky/.m2/repository/org/lwjgl/lwjgl/lwjgl-platform/2.9.3/lwjgl-platform-2.9.3-natives-osx.jar
/Users/jeff.rabovsky/.m2/repository/net/java/jinput/jinput-platform/2.0.5/jinput-platform-2.0.5-natives-windows.jar
/Users/jeff.rabovsky/.m2/repository/net/java/jutils/jutils/1.0.0/jutils-1.0.0.jar
/Users/jeff.rabovsky/.m2/repository/net/java/jinput/jinput-platform/2.0.5/jinput-platform-2.0.5-natives-osx.jar
/Users/jeff.rabovsky/.m2/repository/org/lwjgl/lwjgl/lwjgl-platform/2.9.3/lwjgl-platform-2.9.3-natives-windows.jar
/Users/jeff.rabovsky/.m2/repository/org/jcraft/jorbis/0.0.17/jorbis-0.0.17.jar
/Users/jeff.rabovsky/.m2/repository/net/java/jinput/jinput-platform/2.0.5/jinput-platform-2.0.5-natives-linux.jar
/Users/jeff.rabovsky/.m2/repository/jline/jline/2.14.6/jline-2.14.6.jar
/Users/jeff.rabovsky/.m2/repository/com/badlogicgames/gdx/gdx/1.9.14/gdx-1.9.14.jar
/Users/jeff.rabovsky/.m2/repository/org/lwjgl/lwjgl/lwjgl/2.9.3/lwjgl-2.9.3.jar
/Users/jeff.rabovsky/.m2/repository/com/badlogicgames/gdx/gdx-backend-lwjgl/1.9.14/gdx-backend-lwjgl-1.9.14.jar

jbundler test classpath:
------------------------
	--- empty ---

jbundle complete !

$ bundle exec bin/hello_libgdx_jruby

However, if I warble in the same directory and run the resulting jar, the game crashes:

$ bundle exec warble
rm -f hello_libgdx_jruby.jar
Creating hello_libgdx_jruby.jar
$ java -jar hello_libgdx_jruby.jar
Exception in thread "LWJGL Application" java.lang.NoClassDefFoundError: org/lwjgl/opengl/Display$2
	at org.lwjgl.opengl.Display.<clinit>(Display.java:126)
	at com.badlogic.gdx.backends.lwjgl.LwjglGraphics.setVSync(LwjglGraphics.java:643)
	at com.badlogic.gdx.backends.lwjgl.LwjglApplication$1.run(LwjglApplication.java:125)
Caused by: java.lang.ClassNotFoundException: org.lwjgl.opengl.Display$2
	at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
	... 3 more
AL lib: (EE) alc_cleanup: 1 device not closed

Please let me know if more information is needed. Thanks for your help.