Clirr Maven Plugin
Clirr is a tool that checks Java libraries for binary and source compatibility with older releases. Basically you give it two sets of jar files and Clirr dumps out a list of changes in the public API. The clirr-maven-plugin can be configured to break the build, if it detects incompatible api changes. In a continuous integration process, the clirr-maven-plugin can automatically prevent accidental introduction of binary or source compatibility problems. Additionally, the plugin can generate a report as part of the generated site.