code: @SuppressWarnings("unchecked")
    @NonNull
    public final GenericType<? extends T> getSubtype(@NonNull Class<?> subclass) {
      return new GenericType(token.getSubtype(subclass));
    }
docs: Returns subtype of {@code this} with {@code subclass} as the raw class. For example, if this is
  {@code Iterable<String>} and {@code subclass} is {@code List}, {@code List<String>} is
  returned.