From ngmic...@google.com on July 02, 2013 09:12:30

Use the Enforce Bytecode Version Plugin to ensure our dependencies are compatible with Java 5: http://mojo.codehaus.org/extra-enforcer-rules/enforceBytecodeVersion.html The java6 package should obviously enforce Java 6 compatibility. App Engine also requires at least Java 6.

We attempted to do this once, but ran into the following problem:

The Enforcer plugin crashes with a NullPointerException. This seems to be because we specify version numbers in instead of directly on the dependencies.

The following thread appears to be the issue we're facing as well: http://stackoverflow.com/questions/1017019/maven-assembly-plugin-fails-with-nullpointerexception Particularly the comment on the answer: http://stackoverflow.com/questions/1017019/maven-assembly-plugin-fails-with-nullpointerexception#comment826448_1017037

Original issue: http://code.google.com/p/google-http-java-client/issues/detail?id=234