I have created a ComboBox for a soft attribute of WTPart in the create new page. I have done this using data utility.It is showing me the values correctly in the UI screen of Create New WTPart. But the selected value is not getting persisted. Can someone

public class PartComboBoxUtility extends DefaultDataUtility {
@Override
public Object getDataValue(String component_id, Object datum, ModelContext modelContext) throws WTException {

  // Initialize ComboBox UI Component
  Object object = super.getDataValue(component_id, datum, modelContext);
  System.out.println("component_id 111 4444 = = = = = = = "+component_id);
  Object raw_value = modelContext.getRawValue();
  com.ptc.core.lwc.server.PersistableAdapter  nmObject= new com.ptc.core.lwc.server.PersistableAdapter (new WTPart(), null,java.util.Locale.US, null);
  nmObject.load("Country");
  String o=TgsPropertyHelper.getPropertyValue("Country");
    String[] ab=o.split(",");

  ArrayList<String> displayList = new ArrayList<String>();
        ArrayList<String> internalList = new ArrayList<String>();
  ArrayList<String> selectedValue = new ArrayList<String>();
        internalList.addAll(Arrays.asList(ab));
        displayList.addAll(Arrays.asList(ab));
  selectedValue.add((String)raw_value);
  ComboBox comboBox = new ComboBox(internalList,displayList,selectedValue );
  if (modelContext.getDescriptorMode().equals(ComponentMode.CREATE) || modelContext.getDescriptorMode().equals(ComponentMode.EDIT))
  {
   comboBox.setName(component_id);
   comboBox.setColumnName(AttributeDataUtilityHelper.getColumnName(component_id, datum, modelContext));
   comboBox.setId(component_id);
   comboBox.setInternalValues(internalList);
   //  comboBox.setValues(displayList);
     comboBox.setEnabled(true);

   return comboBox;
  }
   return object;

}
private String getValue(String component_id, Object datum, ModelContext mc) throws WTException {

return UtilityHelper.getStringValue(component_id, datum, mc);
}

}