if (node == null) {
      return 0;
    }
    // The cast is safe because we call this method only if hasUpperBound().
    int cmp =
        comparator()
            .compare(uncheckedCastNullableTToT(range.getUpperEndpoint()), node.getElement());
    if (cmp > 0) {
      return aggregateAboveRange(aggr, node.right);
    } else if (cmp == 0) {
      switch (range.getUpperBoundType()) {
        case OPEN: