Bug 126839 [DataBinding] IObservable refactoring
bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/internal/databinding/viewers/TreeViewerUpdatableTreeExtended.java
class ColumnInfo{ 
		boolean converterDefaulted;
		boolean validatorDefaulted;
		boolean cellEditorDefaulted;
	}
	
	class TreeLabelProvider extends LabelProvider implements ITableLabelProvider {
		private Object getValue(Object element, Column column) {
			Object value = treeViewerDescription.getCellModifier().getValue(
					element, Integer.toString(treeViewerDescription.getColumnIndex(element.getClass(), column)));
			return value;
		}
		private Object getConvertedValue(Object element, Column column) {
			String propertyName = column.getPropertyName();
			Object value;
			if (propertyName == null) {
				value = element;
			} else {
				value = getValue(element, column);
			}
			
			Object convertedValue = column.getConverter().convertModelToTarget(
					value);
			return convertedValue;
		}