It seems that the dependency on dev-java/java-sdk-docs got left out of the sun-jdk-1.6.0.04 ebuild. See attached diff. The ebuild now contains no conditional for USE="doc", but "doc" is still in IUSE, leading me to believe this was an error rather than intentional. If I'm wrong, I apologize.
Created attachment 141667 [details] Diff of ebuilds
You're right, I wanted to move it from DEPEND to RDEPEND only but it got mysteriously lost :P Thanks for noticing.