java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String com.example.pppp.onex.InfoWindowData.getTitle()' on a null object reference
                                                                                    at com.example.pppp.onex.CustomInfoWindowAdapter.getInfoContents(CustomInfoWindowAdapter.java:49)

mMap.setOnMarkerClickListener(new GoogleMap.OnMarkerClickListener() {
            @Override
            public boolean onMarkerClick(final Marker marker) {

                db.collection("marcadores")
                        .get()
                        .addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
                            @Override
                            public void onComplete(@NonNull Task<QuerySnapshot> task) {
                                if (task.isSuccessful()) {
                                    for (final QueryDocumentSnapshot document : task.getResult()) {


                                        Log.d(TAG,String.valueOf(marker.getPosition().latitude));

                                        if(String.valueOf(marker.getPosition().latitude).equals(String.valueOf(document.getData().get("latitude"))) && String.valueOf(marker.getPosition().longitude).equals(String.valueOf(document.getData().get("longitude")))){

                                            InfoWindowData info = new InfoWindowData();

                                            info.setTitle(marker.getId());
                                            CustomInfoWindowAdapter customInfoWindow = new CustomInfoWindowAdapter(MapsActivity.this);
                                            mMap.setInfoWindowAdapter(customInfoWindow);

                                            marker.setTag(info);
                                            marker.showInfoWindow();

                                            break;
                                        }

                                    }
                                } else {
                                    Log.w(TAG, "Error getting documents.", task.getException());
                                }
                            }
                        });

                return false;
            }
        });

public CustomInfoWindowAdapter(Context context){
        this.context = context;
    }
    @Override
    public View getInfoContents(final Marker m) {
        //Carga layout personalizado.
        //View v = inflater.inflate(R.layout.infowindow_layout, null);
        View v = ((Activity)context).getLayoutInflater()
                .inflate(R.layout.infowindow_layout, null);
        InfoWindowData infoWindowData = (InfoWindowData) m.getTag();
            TextView title = ((TextView)v.findViewById(R.id.infoWindowAdapterTextView));
                title.setText(infoWindowData.getTitle());
        return v;
    }

public class InfoWindowData {
    private String title;

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

}