CMSDialog was never API.
final OperationAgent operationAgent = specialistsBroker.requireSpecialist(OperationAgent.TYPE);
final RequestOperation operation = operationAgent.getOperation(RequestOperation.TYPE);
final RequestOperation.Answer yes = operation.addYes();
final RequestOperation.Answer no = operation.addNo();
final RequestOperation.Answer ok = operation.addOk();
final RequestOperation.Answer answer = operation.perform("your question text showing in the request operation dialog.");
if (answer == yes) {
...
}
...