Identify artifacts corresponding to "supported" API modules. Generate aggregated JavaDoc by fetching the source JAR for each API artifact.
Enable APIViz if possible; use JBoss.org theme if possible.
Javadoc'd packages should be grouped by API.
It is also important that JDK classes are properly linked. This might mean linking to oracle's doc site for JavaSE like many projects do, or perhaps using locally-generated javadoc from OpenJDK perhaps.
Just to keep info on how to: