//
  // Requests for TLS client certificates typically request: "digital signature", "key encipherment", "client auth".
  //
  // Requests for TLS serving certificates typically request: "key encipherment", "digital signature", "server auth".
  //
  // Valid values are:
  //  "signing", "digital signature", "content commitment",
  //  "key encipherment", "key agreement", "data encipherment",