// ExpireDelegationTokenRequest is a request to change the expiry timestamp
// of a delegation token. Note that a client using a token cannot expire its
// own token.
ExpireDelegationTokenRequest => key 40, max version 2, flexible v2+
  // HMAC is the HMAC of the token to change the expiry timestamp of.
  HMAC: bytes
  // ExpiryPeriodMillis changes the delegation token's expiry timestamp to
  // now + expiry time millis. This can be used to force tokens to expire
  // quickly, or to allow tokens a grace period before expiry. You cannot
  // add enough expiry that exceeds the original max timestamp.
  ExpiryPeriodMillis: int64

// ExpireDelegationTokenResponse is a response to an ExpireDelegationTokenRequest.
ExpireDelegationTokenResponse =>
  // ErrorCode is any error that caused the request to fail.
  ErrorCode: int16
  // ExpiryTimestamp is the new timestamp at which the delegation token will
  // expire.
  ExpiryTimestamp: int64
  ThrottleMillis(1)