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in Source or Object form, provided that You meet the following conditions: 

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   * proceed to read the response body with [Response.body]. The response is still live until its
   * response body is [closed][ResponseBody]. The recipient of the callback may consume the response
   * body on another thread.
   *
   * Note that transport-layer success (receiving a HTTP response code, headers and body) does not

  optional TokenRequestStatus status = 3;
}

// TokenRequestSpec contains client provided parameters of a token request.
message TokenRequestSpec {
  // Audiences are the intendend audiences of the token. A recipient of a
  // token must identify themself with an identifier in the list of
  // audiences of the token, and otherwise should reject the token. A
  // token issued for multiple audiences may be used to authenticate