public boolean isServiceRegistered(@Nullable final String subdomain) {
        if (subdomain == null) {
            return false;
        }
        return mucServices.containsKey(subdomain);
    }
Returns true if a MUC service is configured/exists for a given subdomain.

@param subdomain Subdomain of service to check on.
@return True or false if the subdomain is registered as a MUC service.
xmppserver/src/main/java/org/jivesoftware/openfire/muc/MultiUserChatManager.java