@SuppressWarnings("unchecked")
  static <R> CriteriaCreator<R> creator() {
    class Local extends AbstractContextHolder implements Self {
      private Local(CriteriaContext context) {
        super(context);
      }
    }

    return ctx -> (R) new Local(ctx);
  }
Do not match current optional boolean attribute. For empty
optional matching is equivalent to {@link #isPresent()} (not absent), otherwise standard
{@link #isNot(boolean)} (boolean)} matching is used.

@param optional optional boolean to match with
@throws NullPointerException if argument is null
criteria/common/src/org/immutables/criteria/matcher/OptionalBooleanMatcher.java