在Android上的Java中从自定义对象的ArrayList获取GeoPoint时出错（错误）

Question

我已经创建了这个自定义对象

public class MapPin {
    GeoPoint geoPoint;
    String trafficType;
    public MapPin(GeoPoint geoPoint, String trafficType) {
        this.geoPoint = geoPoint;
        this.trafficType = trafficType;
    }
    public GeoPoint getGeoPoint() { return geoPoint; }
    public String getTrafficType() { return trafficType; }
}

我需要将从Firestore获得的GeoPoint转换为新的GeoPoint对象，就像这样。

private void getPins(final FBCallback fbCallback){
        DocumentReference mDocRef = FirebaseFirestore.getInstance().document("Pin/pins");
        mDocRef.get().addOnSuccessListener(new OnSuccessListener<DocumentSnapshot>() {
            @Override
            public void onSuccess(DocumentSnapshot doc) {
                if (doc.exists()) {
                    MarkerOptions options = new MarkerOptions();
                    int pin = doc.getLong("counter").intValue();
                    GeoPoint gp;
                    for(int i = 1; i <= pin; i++) {
                        ArrayList<MapPin> mp = (ArrayList<MapPin>) doc.get("" + i);
                        gp = mp.get(0);
                        //Log.i("ARRAY", ""  + ", " + mp.get(0).geoPoint);
                    }
                }
            }
        });
    }

我也尝试了以下方法。

gp = mp.get(0);
gp = mp.get(0).geoPoint;
gp = mp.get(0).getGeoPoint();

要了解更多，这是我的firestore数据库 。

另外，这是错误。

java.lang.ClassCastException: com.google.firebase.firestore.GeoPoint cannot be cast to com.example.traffigo.MapPin