can't generate api docs for JDK7 updates.
should be able to generate docs for jdk updates. RE builds always build docs in JDK7, unlike earlier JDK releases.
Restriction to NOT build the docs if JDK_UPDATE_VERSION is set should be removed.
Removal of the prohibition for doc builds for update releases is correct, when JDK_UPDATE_VERSION is set
8-na: fix in RE2.0 system not applicable to jdk8 in re3.0 system.