@Nullable
    public MultiUserChatService getMultiUserChatService(@Nonnull final String subdomain) {
        return mucServices.get(subdomain);
    }
Retrieves a MultiUserChatService instance specified by it's subdomain of the server's primary domain. In other
words: if the service is <tt>conference.example.org</tt>, and the server is <tt>example.org</tt>, you would
specify <tt>conference</tt> here.

@param subdomain Subdomain of the conference service you wish to query.
@return The MultiUserChatService instance associated with the subdomain, or null if none found.
xmppserver/src/main/java/org/jivesoftware/openfire/muc/MultiUserChatManager.java