{
  "manageEntity": {
    "action": "Download",
    "entityId": "600306",
    "entityType": "Track",
    "metadata": "{\"cid\":\"\",\"data\":{\"city\":\"Nagoya\",\"region\":\"Aichi\",\"country\":\"Japan\"}}",
    "nonce": "0x0f4574395f624d50e1bf64779ed1484894958a9d54dcd03a0cd3b9475a482cbe",
    "signature": "0x648cb14a67a5d29f5320632a7b47b6f38f39385039750f5f3168adc11c73a9b45a3add1e69fb2fd76e5627e662128ea7f0310165436152aaf7565b88f095a7011b",
    "signer": "0xa4FF47524eAeCBad9664EBcE3a8Ce8eDEcF15c1C",
    "userId": "113039916"
  }
}