Bug 126839 [DataBinding] IObservable refactoring
bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/internal/databinding/viewers/TreeViewerUpdatableTreeExtended.java
columnInfos.put(column, info);
				if (column.getConverter() == null) {
					info.converterDefaulted = true;
					if (column.getPropertyType()!=null) {
						initializeColumnConverter(column,column.getPropertyType());
					} else {
						column.setConverter(new IdentityConverter(String.class));
					}
				}
				if (column.getValidator() == null) {
					info.validatorDefaulted = true;
					initializeColumnValidator(column, column.getPropertyType());
				}
				
				
			}
		}
		if (treeViewerDescription.getCellModifier() == null) {			
			treeViewerDescription.setCellModifier(createCellModifier(dataBindingContext));
		}
		if (columnInfos.isEmpty()) {
			columnInfos=null;
		}
	}
	
	protected Column getColumn(Class instanceType, int columnIndex) {
		return treeViewerDescription.getColumn(instanceType, columnIndex);
	}
	
	protected int addElement(final Object parentElement, int index, final Object value, boolean fire) {