Gpx tracks without timestamp for map matching API

Hi, I am working with the graphhopper map matching. I found one issue, is it possible for the current version (0.10) to handle the gpx tracks without timestamps?

I remember in the earlier version (0.8), it is possible to get around the problem of missing timestamp by using “default speed”

* This method creates a GPXFile object filled with lat,lon values from the
* xml inputstream is.
* @param defaultSpeed if no time element is found the time value will be
* guessed from the distance and this provided default speed in kph.
public GPXFile doImport(InputStream is, double defaultSpeed) {

But this option is not available any more.

Is it forced now to always include timestamp in gpx file for graphhopper map matching api to process the data?

thanks for your answers in advance!