Some of our contribs appear to be lacking for development/support or are missing tests. We should review whether they are even pertinent these days and potentially deprecate and remove them.
One of the things we did in Mahout when bringing in Colt code was to mark all code that didn't have tests as @deprecated and then we removed the deprecation once tests were added. Those that didn't get tests added over about a 6 mos. period of time were removed.
I would suggest taking a hard look at:
(spatial should be gutted to some extent and moved to modules)