Bug 127861 [DataBinding] Mark API provisional
bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/internal/databinding/viewers/TreeViewerUpdatableTreeExtended.java
}
				return null;
			}
			
			public void modify(Object element, String property, Object value) {
				if (element instanceof Item) {
					element = ((Item) element).getData();
				}
				Column column = findColumn(element.getClass(), property);
				if (column == null) {
					return;
				}
				value = column.getConverter().convertTargetToModel(value);
				IValidator columnValidator = column.getValidator();
				if(columnValidator != null){
					String errorMessage = columnValidator.isValid(value);
					if(errorMessage != null){
						dataBindingContext.updateValidationError(dummyListener, errorMessage);
						return;
					}
				}
				new PropertyHelper(column.getPropertyName(), element.getClass()).set(element, value);
				viewer.update(element, new String[] { property } );
			}
		};
	}
	
	private void initializeColumnConverter(Column column, Class propertyType){
		   column.setConverter(dataBindingContext.createConverter(String.class, propertyType, treeViewerDescription));		
	}