Problem setting member variables using callback

[upstarter]

I am trying to use your KalmanKt library, and I was wondering if you could tell me what I'm doing wrong:
I use it like this to set an instance variable on the class that _kalmanProcessor is in, but it does not set the instance variables on member object _heartbeatInfo, can you suggest a fix?:

_kalmanProcessor!!.setLocationCallback(100) {
   kalmanFilterCallback(it)
}

 fun kalmanFilterCallback(locationKt: LocationKt) : LocationInfo? {
   val alt = locationKt.getAltitude()
   val lat = locationKt.getLatitude()
   val lon = locationKt.getLongitude()
   val bearing = locationKt.getBearing()
   val speed = locationKt.getSpeed()

   _heartbeatInfo!!.latitude = lat
   _heartbeatInfo!!.longitude = lon
   _heartbeatInfo!!.heading = bearing
   _heartbeatInfo!!.altitude = alt
   _heartbeatInfo!!.speed = speed

   return _heartbeatInfo!!
 }

[WindSekirun]

This library is no longer maintained. (I plan to archive soon.) However, it does not seem to be understood with the attached code.

After setting the callback, I think I can check whether the location information is injected through the process method, and whether it is actually executed as a breaking point. (KalmanProcessor is an example code, you can control it directly with KalmanFilter)