You haven't specified the minimum java version required to use the precompiled jar file. Running it with java 1.4.2 I get:

rich@lisa:~/tmp> java -jar gsd.jar Exception in thread "main" java.lang.UnsupportedClassVersionError: com/google/singletondetector/Main (Unsupported major.minor version 49.0)

If you're going to compile it to require a particular jvm release, please let us know which one!

Java 1.5 is required to run/compile GSD.

This requirement has been added to the README file, and the build and usage wikis.