In my example, you need a Class to be used as a generic type. "void" is just a keyword, it cannot be used for generic types. You cannot use "new Callable<void>". To correct this, you must use the Void class instead.
Also, Void.TYPE is what will be returned from Method.getReturnType() for methods that return nothing (void). That's probably where the entire class was originally created for, since generics didn't exist until Java 5.0, but Void exists since Java 1.1.