Bug 126839 [DataBinding] IObservable refactoring
bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/internal/databinding/viewers/TableViewerUpdatableCollectionExtended.java
ITableLabelProvider {
		private Object getValue(Object element, Column column) {
			String propertyName = column.getPropertyName();
			if (propertyName == null) {
				return element;
			}
			
			Object value = tableViewerDescription.getCellModifier().getValue(
					element, propertyName);
			return value;
		}
		private Object getConvertedValue(Object element, Column column) {
			IConverter converter = column.getConverter();
			if (converter != null) {
				Object convertedValue = column.getConverter().convertModelToTarget(getValue(element, column));
				return convertedValue;
			}
			return null;
		}
		public Image getColumnImage(Object element, int columnIndex) {
			if (columnIndex < tableViewerDescription.getColumnCount()
					&& columnIndex >= 0) {
				Column column = getColumn(columnIndex);
				IConverter converter = column.getConverter();
				if (converter != null && converter.getTargetType().equals(ViewerLabel.class)) {
					ViewerLabel viewerLabel = (ViewerLabel) getConvertedValue(
							element, column);
					if (viewerLabel != null) {