@HandleAuthorizationDenied(handlerClass = Null.class)
public String getUserEmail() {
    // ...
}

@Component
public class Null implements MethodAuthorizationDeniedHandler {
    @Override
    public Object handle(MethodInvocation methodInvocation, AuthorizationResult result) {
        return null;
    }
}

@HandleAuthorizationDenied(handlerExpression = "null")
public String getUserEmail() {
    // ...
}

@HandleAuthorizationDenied(handlerExpression = "***")
public String getUserEmail() {
    // ...
}