public static void addUserNameProvider(String domain, UserNameProvider provider) {
        providersByDomain.put(domain, provider);
    }
Adds the specified {@link UserNameProvider} as the provider of users of the specified domain.

@param domain   the domain hosted by the UserNameProvider.
@param provider the provider that will provide the name of users in the specified domain.
xmppserver/src/main/java/org/jivesoftware/openfire/user/UserNameManager.java