BackendSessionCB = function(service, cb, err, sinfo) {
  if(err) {
    utils.invokeCallback(cb, err);
    return;
  }

  if(!sinfo) {
    utils.invokeCallback(cb);
    return;
  }
  var sessions = [];
  if(Array.isArray(sinfo)){
      // #getByUid
      for(var i = 0,k = sinfo.length;i<k;i++){
          sessions.push(service.create(sinfo[i]));
      }
  }
  else{
      // #get
      sessions = service.create(sinfo);
  }
  utils.invokeCallback(cb, null, sessions);
}
Export the key/values for serialization.

@api private