
Modern Jass implements a new concept to bring Design by Contract to Java. Basically, it uses Java 5 annotation to specify contracts, the Pluggable Annotation Processing API to validate contracts, and the Bytecode Instrumentation API to enforce contracts.
Modern Jass is new and somehow cool, because:
Go to the Getting Started document to get you feet wet, or learn more about Modern Jass in the following sections. A detailed introduction can be found in this document [pdf].