Bug 127861 [DataBinding] Mark API provisional
bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/databinding/viewers/TreeViewerDescription.java
columns = new ArrayList();
			columnsMap.put(instanceType, columns);
		}
		Column column = new Column(propertyName, cellEditor , validator,
				converter);
		if(columnIndex == -1)
			columns.add(column);			
		else 
			columns.add(columnIndex,column);			
	}
	
	/**
	 * @param instanceType 
	 * @param propertyName
	 * @param cellEditor
	 * @param validator
	 * @param converter
	 */
	public void addColumn(Class instanceType, String propertyName,
			CellEditor cellEditor, IValidator validator, IConverter converter) {
		addColumn(instanceType, -1,propertyName,cellEditor,validator,converter);
	}
	/**
	 * @param instanceType 
	 * @param columnIndex
	 * @param propertyName
	 * @param validator
	 * @param converter
	 */
	public void addColumn(Class instanceType, int columnIndex, String propertyName,