bool((must, should, mustNot, filter) -> {
            filteredLambda.callback(must, filter);
        }, opLambda);
    }

    public void not(OperatorCall<UserCQ> notLambda) {
        not(notLambda, null);
    }

    public void not(final OperatorCall<UserCQ> notLambda, final ConditionOptionCall<BoolQueryBuilder> opLambda) {
        bool((must, should, mustNot, filter) -> notLambda.callback(mustNot), opLambda);

      if (set == null) {
        return ImmutableSet.of();
      }
      ImmutableSet<E> ret = ImmutableEnumSet.asImmutable(set);
      set = null; // subsequent manual manipulation of the accumulator mustn't affect ret
      return ret;
    }
  }

  @GwtIncompatible
  @SuppressWarnings({"rawtypes", "unchecked"})
  static <E extends Comparable<? super E>>