static long defaultExpiration() {
    return Instant.now().getEpochSecond() + DEFAULT_EXPIRATION_PERIOD_SEC;
  }
Expiration is not standardised. We use Geth's expiration period (60 seconds); whereas Parity's
is 20 seconds.
ethereum/p2p/src/main/java/org/hyperledger/besu/ethereum/p2p/discovery/internal/packet/PacketData.java