I am implementing Firebase Recyclerview UI in my application. I have implemented a recyclerview adapter and it shows me following exception. 
Following is my adapter code : 

```
FirebaseRecyclerAdapter<DataSnapshot, MyHolder> recyclerAdapter = new FirebaseRecyclerAdapter<DataSnapshot, MyHolder>(
                DataSnapshot.class,
                R.layout.row_slots,
                MyHolder.class,
                databaseReference.child("slots").child(uid).child(dayOfWeek).child("time")
        ) {
            @Override
            protected void populateViewHolder(MyHolder viewHolder, DataSnapshot model, int position) {

                System.out.println("Key : "+model.getKey());

            }

        };

```

It is showing following exception : 
[![enter image description here](https://i.stack.imgur.com/stn0C.png)](https://i.stack.imgur.com/stn0C.png)

How can I get a snapshot value using FirebaseRecyclerAdapter?