Download net.sf.chex4j JAR files with all dependencies

chex4j-core is a javaagent so testing it requires the built jar to be added to the jvm start options. Putting the tests in a separate module ensures that the core jar is available during the build time of the test module.

The chex4j core runtime classes.

Chex4j allows you to document and enforce @pre and @post conditions of method calls with runtime class file instrumentation. Conditions run as fast as normal code. Chex4j runs as a class load time javaagent. Optionally the instrumented classes may be output to disk for deployment.