function requestRateUpdate()
    external
    ensureAuthorizedRequester()
  {
    Chainlink.Request memory request;
    bytes32 requestId;
    uint256 oraclePayment = paymentAmount;

    for (uint i = 0; i < oracles.length; i++) {
      request = buildChainlinkRequest(jobIds[i], this, this.chainlinkCallback.selector);
      requestId = sendChainlinkRequestTo(oracles[i], request, oraclePayment);
      requestAnswers[requestId] = answerCounter;
    }
    answers[answerCounter].minimumResponses = minimumResponses;
    answers[answerCounter].maxResponses = uint128(oracles.length);
    answerCounter = answerCounter.add(1);
  }