Refactor packages of a jar

I am having some troubles with a jar, and I want to rename all clases to avoid conflicts, but I only have the final jar :(

Classes in jar are in p开发者_如何学编程ackage as it:

org.foundation and I want to be available in another jar as

org.foundation.oldversion

Is there any tool to do it ?

I don't want to decompile.

Have you tried jarjar

You can avoid problems where your library depends on a specific version of a library, which may conflict with the dependencies of another library.