String selection = comboBox.getValue(comboBox.getSelectedIndex());
if (selection != null && !selection.equals("")) {
// create a select statement
eventBus.fireEventFromSource(
new StatementEvent(
CommonQNames.SELECT_ID,
"selected.entity",
selection), // synthetic key (convention), see LoadResourceProcedure
getInteractionUnit().getId());
previousSelection = selection;
} else {
// clear the select statement
eventBus.fireEventFromSource(
new StatementEvent(
CommonQNames.SELECT_ID,
"selected.entity",
null),
getInteractionUnit().getId());