docs: private N overflowTreatment(N node, IndexTreePath<SpatialEntry> path, int[] splitAxis) {
      if(node.isSuperNode()) {
        // only extend supernode; no re-insertions
        assert node.getCapacity() == node.getNumEntries();
        assert node.getCapacity() > dirCapacity;
        node.growSuperNode();
        return null;
      }
      // Handled by reinsertion?
      if(settings.getOverflowTreatment().handleOverflow(this, node, path)) {
        return null;
      }
      return split(node, splitAxis);
    }