Extrinsic 4542-1

{
  "heartbeat": {
    "blockNumber": 4540,
    "sessionIndex": 75,
    "validatorsLen": 4,
    "authorityIndex": 0
  },
  "signature": "0x68c8a9fbcc3acfbedcfef6da01d9c072789b64ecd7e8c0caff0087f1186e185d73762eec7c019be16753e0426b3aac5e524e29cace860f44cc7ea71636a64b8c"
}