docs: public static <P, T> PositionFactory<P, T> optional(BiConsumer<? super P, ? super T> mutator) {
          Validate.isInstanceOf(Mutator.class, mutator, "Cannot detect property from %s; missing %s?", mutator,
              THERIAN_PROPERTY_METHOD_WEAVER);
          final boolean optional = true;
          return new PositionFactory<>(((Mutator<? super P, ? super T>) mutator).propertyName, optional);
      }