code: void onColumnTypeChanged(@Observes ValueChangeEvent<ColumnType> event) {
          PortablePreconditions.checkNotNull("ValueChangeEvent<ColumnType>",
                                             event);
          if (event.getContext().equals(columnType)) {
  
              // Update the help tooltip when the column type changes
              String columnTypeDescr = getColumnTypeDescription(event.getValue());
              columnType.setHelpContent(DataSetEditorConstants.INSTANCE.attributeColumnType(),
                                        columnTypeDescr,
                                        Placement.RIGHT);
          }
      }
docs: Listen to changes in the column type