/**
   * Collects parent types from a subtype.
   *
   * @param <K> The type "kind". Either a TypeToken, or Class.
   */
  private abstract static class TypeCollector<K> {

    static final TypeCollector<TypeToken<?>> FOR_GENERIC_TYPE =
        new TypeCollector<TypeToken<?>>() {
          @Override
          Class<?> getRawType(TypeToken<?> type) {
            return type.getRawType();
          }