Extrinsic 4421-1

{
  "heartbeat": {
    "blockNumber": 4420,
    "sessionIndex": 73,
    "validatorsLen": 1,
    "authorityIndex": 0
  },
  "signature": "0x02143607bb4dde6295ab46255c7589ac430312e1ea7887018a3ae0412914600a0ec16ebb7af28dc74992698eaf28cc1d1292b3a0322732338cfb1274b1656082"
}