UPS REST _parseRestResponse doesn't return rates when only one service is available for a destination

[iamniels]

After switching to UPS REST API, no rates were available for Cyprus. For Cyprus only one service is available on our UPS contract. In this case the response from UPS is:

"RatedShipment": {
      "Service": {
        "Code": "65",
        "Description": ""
      },
      "RatedShipmentAlert": {
        "Code": "110971",
        "Description": "..."
      },

Instead of:

"RatedShipment": [
      {
        "Service": {
          "Code": "07",
          "Description": ""
        },

So when there is only one service, an object is returned instead of an array.

UPS::_parseRestResponse doesn't handle this case properly.

Can be fixed like this:

    protected function _parseRestResponse(string $rateResponse)
    {
        $costArr = [];
        $priceArr = [];
        $errorTitle = '';
        if (strlen($rateResponse) > 0) {
            $rateResponseData = json_decode($rateResponse, true);
            if (@$rateResponseData['RateResponse']['Response']['ResponseStatus']['Description'] === 'Success') {
                $arr = $rateResponseData['RateResponse']['RatedShipment'] ?? [];
                if(isset($arr['Service'])){
                    $arr = [$arr];
                }