code: public <T extends ICDKObject> Set<Class<?>> implementorsOf(Class<T> intf) {
          Set<Class<?>> implementations = new HashSet<Class<?>>(5);
          for (ConstructorKey key : lookup.getConstructors(intf)) {
              implementations.add(get(key).getDeclaringClass());
          }
          return implementations;
      }
docs: Access the registered implementations for a given interface.
  
  @param intf an interface which has registered implementations in the
  factory
  @param <T>  the type of the interface
  @return set of implementation classes (empty if none found)