DNA has a fairly large number of classes, not all of which are intended to be stable. Although some examples and documentation "best practices" for utilizing the API are provided, there is no explicit contract in the API that indicates which portions of the API are expected to remain stable and supported over time.
A comparable discussion was occurring on the jboss-development mailing list (https://lists.jboss.org/mailman/listinfo/jboss-development) Vol. 36 Issue 8 et al. It appears that Eclipse uses annotations to provide this information. These annotations (http://www.opends.org/promoted-builds/2.0.0-RC1/javadoc/org/opends/server/types/PublicAPI.html and http://www.eclipse.org/pde/pde-api-tools/) were tossed around in the discussion.