At the moment, we make use of a fork of Apache Commons TypeUtils, a fork of GenTyRef, and have a dependency on Google Guava (TypeToken) to enable the generics handling involved in Op matching. The ongoing work on #2 will probably add yet another dependency, GeAnTyRef.
GeAnTyRef may have the potential to replace one or more of the previously mentioned dependencies (e.g., it has an own TypeToken), or to even get rid of all of the generics-related functionality of org.scijava.util.Types. It deserves some more investigation to see if it meets all our requirements.