@Override
    public User loadUser(String username) throws UserNotFoundException
    {
        final UserProvider userProvider;
        try {
            userProvider = getUserProvider( username );
        } catch (RuntimeException e){
            throw new UserNotFoundException("Unable to identify user provider for username " + username, e);
        }
        return userProvider.loadUser( username );
    }
Returns whether <em>all</em> backing providers require an email address to be set on User objects. If at least
one provider does not, this method returns false.

@return true when all backing providers require an email address to be set on User objects, otherwise false.
xmppserver/src/main/java/org/jivesoftware/openfire/user/UserMultiProvider.java