Extrinsic 18500-1

{
  "heartbeat": {
    "blockNumber": 18498,
    "sessionIndex": 308,
    "validatorsLen": 4,
    "authorityIndex": 2
  },
  "signature": "0x36ebb82f0a19456af0e497df1c75c4ae577dba29c0bc1d6579e6176d4800890bd0a584e7c4da9383c58f857341aea4495726e701474e2fee1a0d575984c16481"
}