// If the user is not the owner, throw a 403 error.
Profile profile = ofy().load().key(Key.create(Profile.class, userId)).now();
if (profile == null ||
!conference.getOrganizerUserId().equals(userId)) {
return new TxResult<>(
new ForbiddenException("Only the owner can update the conference."));
}
conference.updateWithConferenceForm(conferenceForm);
ofy().save().entity(conference).now();
return new TxResult<>(conference);
}