code: private N overflowTreatment(N node, IndexTreePath<E> path) {
      if(settings.getOverflowTreatment().handleOverflow(this, node, path)) {
        return null;
      }
      return split(node);
    }
docs: Treatment of overflow in the specified node: if the node is not the root
  node and this is the first call of overflowTreatment in the given level
  during insertion the specified node will be reinserted, otherwise the node
  will be split.
  
  @param node the node where an overflow occurred
  @param path the path to the specified node
  @return the newly created split node in case of split, null in case of
  reinsertion