Cannot set -sourcepath to add paths for inherited javadocs

In version 1.5 of the javadoc plugin it was possible to specify:

maven.javadoc.additionalparam=-sourcepath /usr/java/src

so that you could include source paths where you had used the

{@inheritDoc} tag. Unfortunately this is broken in version 1.7. A look at the jelly source shows that 1.7 uses <ant:sourcepath> to define where the compiled source files live. It does not seem possible to now define other paths to be set for sourcepath. Note that javadoc only allows one -sourcepath argument (it complains if you give more), and since this is controlled by the plugin you cannot extend it.

It would be good if there was a:

maven.javadoc.extrasourcepath=path1;path2;...

setting that would append to the javadoc -sourcepath argument. Without some sort of modification I cannot see how {@inheritDoc}

tags can work (esp. since Sun fixed them up in 1.5).