isValid method
Checks if this VERSION_NEGOTIATION packet is valid
Implementation
bool isValid() {
return supportedVersions.isNotEmpty &&
destinationCid.length >= ConnectionId.minCidLength &&
destinationCid.length <= ConnectionId.maxCidLength &&
sourceCid.length >= ConnectionId.minCidLength &&
sourceCid.length <= ConnectionId.maxCidLength;
}