We present a realization of multi software product lines in the Java programming language that permits full interoperability and hierarchical dependencies among multiple product variants. This concept, called variability modules (VM), is implemented in terms of an architectural pattern in Java and does not require any pre-processing or language extension. It can be used with any Java development environment. The VM architectural pattern comes with a dedicated UML profile, which makes it possible to present variability to non-technical stakeholders. We evaluate our approach with the help of a real-world case study. © 2021 ACM.