FormData formResult = formService.executeFormActions(form, formData);
// check for validation errors
if (formResult.getFormResult(AssignmentWithdrawButton.DEFAULT_ID) != null) {
// withdraw assignment
workflowManager.assignmentWithdraw(activityId);
} else if (formResult.getFormResult(AssignmentCompleteButton.DEFAULT_ID) != null) {
// complete assignment
Map<String, String> variableMap = AppUtil.retrieveVariableDataFromMap(getRequestParameters());
formResult = appService.completeAssignmentForm(form, assignment, formData, variableMap);