Extrinsic 1520-1

{
  "heartbeat": {
    "blockNumber": 1518,
    "sessionIndex": 25,
    "validatorsLen": 4,
    "authorityIndex": 2
  },
  "signature": "0xa48e87b343c32aadaf5bbd6a632b4d4bb00f44fd784eb8d665bcb32f0cc696031658cb114c472847c7481ab16240206b4c52432403a5f1b8ca37583ea5341985"
}