Reliable way to get "to" and "from" for a warm transferred call.

When the original caller is transferred from one extension to another extension(or to any other number), I couldn't find a reliable way to identify, from whom to whom the call was transferred.

From the call log API(/restapi/v1.0/account/~/call-log?&view=Detailed) , Only info related to call transfer is in call leg as given below:

{
      "action": "Transfer",
      "direction": "Outbound",
      "duration": 21,
      "extension": {
        "id": 249697004,
        "uri": "https://platform.devtest.ringcentral.com/restapi/v1.0/account/249331004/extension/249697004"
      },
      "from": {
        "extensionId": "249697004",
        "name": "Nanda Kumar"
      },
      "legType": "TransferCall",
      "result": "Call connected",
      "startTime": "2019-07-18T08:46:36.185Z",
      "to": {
        "location": "Los Angeles , CA"
      },
      "transport": "PSTN",
      "type": "Voice"
}

Which does not have the proper `to` and `from` values.