The exam objective says "authenticate the caller" for the implementing security objective.
But in JSR 318, it only covers authorization (method permission, declare roles, role link...).
I don't see any authentication in this specification. Maybe, getCallerPrincipal() is related to authentication.
Yes, you are right the emphasis is on authorization not on authentication.
You should know a bit about the EJBContext.getCallerPrincipal() in the different EJB types and what the the @RunAs annotation does with the authenticated user (e.g is the principal name still the same or not)
The obvious trick question related to this is whether the EJBContext.getCallerPrincipal() would return null or an empty Principal when the user is unauthenticated.