Never refer to the same JAR using Class-Path from two different modules. (It will get loaded twice and could cause strange problems.) If you think you need to, generally this just means you have not factored out your module dependencies thoroughly: split off a third module to hold the library.
Java expert Jeff Friesen completes a two-part series about the problems of developing Android apps with JDK 7. Part 2 focuses on supporting Java 7-specific language features.
A. Leitner, M. Oriol, A. Zeller, I. Ciupa, and B. Meyer. Proceedings of the Twenty-second IEEE/ACM International Conference on Automated Software Engineering, page 417--420. New York, NY, USA, ACM, (2007)