The solution that we've generally used in the SpringSource bundle repository is to use fragments. E.g. both the Hibernate annotations bundle (http://tinyurl.com/4pdy2r) and the core Hibernate bundle (http://tinyurl.com/4x6fxf) export the org.hibernate package, so the Hibernate annotations bundle is defined as a fragment of the core Hibernate bundle. Here's the relevant header from the annotation bundle's manifest:
thank you very much.