geIceCandidates
  // generateAudioReceiveOnlyOffer

  /*
    4.3.2.  Interface Definition
      interface RTCPeerConnection : EventTarget {
        ...
        readonly  attribute RTCIceGatheringState   iceGatheringState;
                  attribute EventHandler           onicegatheringstatechange;
      };

    4.4.2.  RTCIceGatheringState Enum
      enum RTCIceGatheringState {
        "new",
        "gathering",
        "complete"
      };

    5.6.  RTCIceTransport Interface
      interface RTCIceTranspo