func Register(s grpc.ServiceRegistrar) (cleanup func(), _ error)
Register registers the set of admin services to the given server.
The returned cleanup function should be called to clean up the resources allocated for the service handlers after the server is stopped.
Note that if `s` is not a *grpc.Server or a *xds.GRPCServer, CSDS will not be registered because CSDS generated code is old and doesn't support interface `grpc.ServiceRegistrar`. https://github.com/envoyproxy/go-control-plane/issues/403