everything works (linux)

$ java -jar ~/.m2/repository/org/jruby/jruby-complete/1.5.0/j
ruby-complete-1.5.0.jar -S jrubyc -t $PWD/target/jrubyc-generated-sources/ -d $PWD/src/main/ruby --java /home/kristian/projects/jruby-maven-plugins/jruby-maven-plugin/src/it/generate-java-and-compile/src/main/ruby 

Compiling all in '/home/kristian/projects/jruby-maven-plugins/jruby-maven-plugin/src/it/generate-java-and-compile/src/main/ruby'...
Generating Java class MyReply to /home/kristian/projects/jruby-maven-plugins/jruby-maven-plugin/src/it/generate-java-and-compile/target/jrubyc-generated-sources/com/otherexample/MyReply.java

or

$ java -jar ~/.m2/repository/org/jruby/jruby-complete/1.5.0/j
ruby-complete-1.5.0.jar -S jrubyc -t target/jrubyc-generated-sources/ -d src/main/ruby --java src/main/ruby

Compiling all in '/home/kristian/projects/jruby-maven-plugins/jruby-maven-plugin/src/it/generate-java-and-compile/src/main/ruby'...
Generating Java class MyReply to target/jrubyc-generated-sources/com/otherexample/MyReply.java

no file no output (windows)

java.exe -jar D:\work\.m2\repository\org\jruby\jruby-complete\1.5.0\jruby-complete-1.5.0.jar -S jrubyc -d D:\work\dev\workspace\codingkata\templates\generate-java-and-compile\src\main\ruby --java -t D:\work\dev\workspace\codingkata\templates\generate-java-and-compile\target\jrubyc-generated-sources D:\work\dev\workspace\codingkata\templates\generate-java-and-compile\src\main\ruby

or

java.exe -jar D:\work\.m2\repository\org\jruby\jruby-complete\1.5.0\jruby-complete-1.5.0.jar -S jrubyc --java -t target\jrubyc-generated-sources src\main\ruby

or

java.exe -jar D:\work\.m2\repository\org\jruby\jruby-complete\1.5.0\jruby-complete-1.5.0.jar -S jrubyc --java -t target\jrubyc-generated-sources -d src\main\ruby src\main\ruby