code: func getDiscovery(opts *ServerOptions) Handler {
  	return func(w io.Writer, _ io.Reader, _ httprouter.Params) error {
  		resp := DiscoveryResponse{
  			ApiVersion:                   ApiVersion,
  			SupportedSubjectRequestTypes: opts.SubjectTypes,
  			SupportedIdentities:          opts.Identities,
  			ProcessorCertificate:         opts.ProcessorCertificateUrl,
  		}
  		return json.NewEncoder(w).Encode(resp)
  	}
  }
docs: // discovery