I'd like to start using the Clirr Maven plugin  to make sure that we don't accidentally break backwards compatibility in our public APIs, most notably in jackrabbit-api and jackrabbit-jcr-commons.
Also, we should start explicitly managing the API versions exposed as a part of the OSGi package metadata. Currently all our public packages simply get the latest project version as their version number, but it would be better if the version was explicitly managed and only updated if the API actually changes. To do this I propose we use @Version annotations from the bnd tool on the package-info.java files in all packages considered a part of our public API.
The Clirr plugin should flag all changes made in the API, so we have an easy way to tell which packages need to have their version numbers updated.