code: @Override
  	protected String initValuesImpl(final FieldCase ca) {
  		String keyValue = keyConstraint.initValues(ca);
  		selectedConstraint = map.get(keyValue);
  		if (selectedConstraint == null) {
  			selectedConstraint = map.get(DEFAULT_KEY);
  		}
  		if (selectedConstraint != null) {
  			return selectedConstraint.initValues(ca);
  		}
  		return null;
  	}
docs: This method first calls {@link #initValues(FieldCase)} on the KeyConstraint and then
  determines the matching sub-constraint. If there is one it will be subsequently initialized.