Some typeUtils methods can result in an IllegalArgumentException and this is not documented.

Some Types methods that take TypeMirror's as paramaters will result in the implementation of a IllegalArgumentException when the right TypeMirrors are not passed in. eg., if IsAssignable(TypeMirror, TypeMirror) is passed a TypeMirror that represents an ExecutableElement, an IllegalArgumentException will be thrown.
I'd think this should be documented and/or part of the methods' throws clause.