@Nullable
    public synchronized Beacon track(@NonNull Beacon beacon) {
        Beacon trackedBeacon = null;
        if (beacon.isMultiFrameBeacon() || beacon.getServiceUuid() != -1) {
            trackedBeacon = trackGattBeacon(beacon);
        }
        else {
            trackedBeacon = beacon;
        }
        return trackedBeacon;
    }
@Test
    public void gattBeaconExtraDataIsNotReturned() {
        Beacon extraDataBeacon = getGattBeaconExtraData();
        ExtraDataBeaconTracker tracker = new ExtraDataBeaconTracker();
        Beacon trackedBeacon = tracker.track(extraDataBeacon);
        assertNull("trackedBeacon should be null", trackedBeacon);
    }