is vuvuzela.io must to write in config-server-state as "Registrar"？

[FradeMime]

I plan to deploy the alpenhorn server locally。
the config-server-state is like this:
{ "Version": 1, "Created": "2023-02-05T15:50:15.375810566-05:00", "Expires": "2028-02-05T15:50:15.375810566-05:00", "PrevConfigHash": "", "Service": "AddFriend", "Inner": { "Version": 2, "Coordinator": { "Key": "kq0jmkh6r5hz5pp5z3r2jcm6ff7r8z693g72h1h81yqyh3cjbbcg", "Address": "localhost:8000" }, "PKGServers": [ { "Key": "v2j5v6f2p20xvfvqskxshydye7n7xps3frxe4vkqedysb147dj20", "Address": "localhost:8000" } ], "MixServers": [ { "Key": "5qnp2ac88cshy9p51a4fag0q5kqbjv3a12qcdtng31t9cp35qpzg", "Address": "localhost:28000" } ], "CDNServer": { "Key": "c37zge59xj5ekdkb3ywyg4r5kc4bv1zrfgcx8wpbdddrfs46fr5g", "Address": "localhost:8080" }, "Registrar": { "Key": null, "Address": "" } }, "Guardians": [ { "Username": "gfkd", "Key": "jf6f58kbrvwzy4xsdvawq2ca2s3dd4r9g2tf4584cdysx5cyy05g" } ], "Signatures": { "jf6f58kbrvwzy4xsdvawq2ca2s3dd4r9g2tf4584cdysx5cyy05g": "w2s0zekey8y5wtqrp6gxp74tg444c88mpk8snhsxw75n9emgtrse20a2est6st19h837dp2ya61v4pwgzb6ebw493f9ycb35xtpxa18" } }

"Registrar": {
"Key": null,
"Address": ""
}

the register-server must be "vuvuzela.io"？
can i use localhost regsiter