code: public Partition<Step<T>> getOrCreatePartition()
     {
        Node node = childNode.getOrCreate("partition");
        Partition<Step<T>> partition = new PartitionImpl<Step<T>>(this, "partition", childNode, node);
        return partition;
     }
docs: If not already created, a new <code>partition</code> element with the given value will be created.
  Otherwise, the existing <code>partition</code> element will be returned.
  @return  a new or existing instance of <code>Partition<Step<T>></code>