The transportId property of the RTCIceCandidatePairStats dictionary uniquely identifies the RTCIceTransport object that was inspected to obtain the transport-related statistics contained in the stats object.
A string which uniquely identifies the RTCIceTransport object from which the transport-related data was obtained for the statistics contained in this RTCIceCandidatePairStats object.
The transport-related statistics come from the RTCTransportStats dictionary.