It would be nice if javadoc did something more intelligent with [labels for] references to classes not defined [documented] in the current run of javadoc. This comes up all the time when using javadoc on anything except the JDK.
Simple uses of String in the API turn into java.lang.String in the javadocs,
which is excessively verbose and ugly.

Maybe we need an option to build an external link table [mapping simple
class names to fully-qualified names]? For instance,
The JavaMail API's depend on the JavaBeans Activation Framework,
located in activation.jar. It might be nice to have a separate external
references HTML page so that a reference to the class "DataHandler" in
the JavaMail source can turn into a link to an item on this external
reference page that explains that "DataHandler" is really
"javax.activation.DataHandler". Similarly for all the JDK classes. One
external references page for each "classpath element" would be reasonable.