public void writeTo(final RLPOutput out) {
    out.startList();
    out.writeUnsignedByte(getVersion());
    out.writeBytes(wrap(getClientId().getBytes(StandardCharsets.UTF_8)));
    out.writeList(getCapabilities(), Capability::writeTo);
    out.writeIntScalar(getPort());
    out.writeBytes(getNodeId());
    out.endList();
  }
This value is meant to represent the port at which a peer is listening for connections. A value
of zero means the peer is not listening for incoming connections.

@return The tcp port on which the peer is listening for connections, 0 indicates the peer is
    not listening for connections.
ethereum/p2p/src/main/java/org/hyperledger/besu/ethereum/p2p/rlpx/wire/PeerInfo.java