private Row<V> doGetRow(int index) {
		Row<V> row = rowsByIndex.get(index);
		if (row == null) {
			row = new Row<>(index);
			rowsByIndex.put(index, row);
		}
		return row;
	}
Returns the rows in this location map, sorted from lowest index to highest 

@return the rows in this location map, sorted from lowest index to highest
Ghidra/Framework/Graph/src/main/java/ghidra/graph/viewer/layout/LayoutLocationMap.java