connectionId property
Note: ECN codepoint marking at the IP layer (ECT(0)=2, ECT(1)=3) is not
implemented because Dart's RawDatagramSocket does not expose platform-
specific socket options such as IP_TOS (Linux) or IP_TOS/Traffic Class (Windows). ECN validation via AckEcnFrame is fully supported.
The first active connection ID, or null if none have been issued.
Implementation
/// The first active connection ID, or null if none have been issued.
List<int>? get connectionId {
final ids = _cidManager.activeIds;
if (ids.isEmpty) return null;
return ids.first.connectionId;
}