code: protected void insert(Path.Item item) throws IOException {
  		if (item.id().parent() != id) {
  			throw new IllegalArgumentException(
  					"Cannot insert with incorrect Path.Item (" + item.id() + ") into AbstractFolder (" + id + ")");
  		}
  		updateContents();
  		//
  		Path.ID id = item.id();
  		int index = binarySearch(contents, nentries, id);
  
  		if (index < 0) {
  			index = -index - 1; // calculate insertion point
  		} else {
  			// indicates already an entry with a different content type
  		}
  		// Insert item at given index
  		insert(index,item);
  	}
docs: Insert a newly created item into this folder. Observe we assume
  <code>entry.id().parent() == id</code>.
  
  @param item