Perhaps adapting the C++ code from http://www.cgal.org/Manual/latest/doc_html/cgal_manual/packages.html#Pkg:StraightSkeleton2
Beside doing the Google search for you to see if there is something equivalent for Java, I can't help more, although I find the topic interesting.
Just in case, check if Toxilibs hasn't something like that, this awesome library is full of such algorithms.

I actually managed to pull it off with Superskein by repeating the shell(er) process until java "Area" was empty and increasing the "dirCount" to 40 or 50 in some cases. Not as pretty as simple skeleton, but it should work for what I need.  Would love to know if someone has done it with Simple Skeletons in processing.

I was looking for a java implementation with this algorithm, but nothing that works finded, only a plugin of imageJ.