SimpMessageHeaderAccessor#getUser is now nullable. How to handle?

[stefanos-kalantzis]

I couldn't find a better place to open this... Please redirect me if there is.

spring-messaging, since v5.0.0, has marked method SimpMessageHeaderAccessor#getUser as @Nullable.
Which actually causes Findbugs to fail with code similar to your example, and rightfully so.

Specifically here: PresenceEventListener#handleSessionConnected

String username = headers.getUser().getName();

My question is how is this supposed to be handled properly? (i.e. when #getUser returns null)
Should the code throw an exception? do nothing?
And what does it actually mean that the user is null in this context?

Principal principal = headers.getUser();
if (principal == null) {
    // what should happen here ?
}

Thanks !