Rather than answering that you “have been quite fortunate and have never had a conflict at work,” which can appear to be disingenuous or show that you lack experience in dealing with workplace conflict, instead answer in a way that shows that you are a team player and possess strong interpersonal skills. You could highlight your ability to listen to the opinions of others, negotiate, persuade, and build consensus among your team. Negative sounding questions are often great opportunities to highlight positive attributes!