Android - Whole data is not getting stored in Firebase Database

I wanna know why my whole data is not getting stored in Firebase Database? Here is a Screenshot of of my data.

Here is The Code

private void sendMessage() {
        DatabaseReference db = FirebaseDatabase.getInstance().getReference().child("Message");
        String message = editTextMessage.getText().toString();
        if (message.isEmpty()) {
            Toast.makeText(this, "Text cannot be empty", Toast.LENGTH_LONG).show();
        } else {
           Messages chat = new Messages(user.getUid(), friendId, message, false);
           String chatID = db.push().getKey();
           db.child(chatID).setValue(chat);
           editTextMessage.setText("");
        }
    }

My Model Class

public class Messages {
    String senderId, receiverID, message;
    boolean isSeen;

    public Messages(){}

    public Messages(String senderId, String receiverID, String message, boolean isSeen) {
        this.senderId = senderId;
        this.receiverID = receiverID;
        this.message = message;
        this.isSeen = isSeen;
    }

    public boolean isSeen() {
        return isSeen;
    }

    public void setSeen(boolean seen) {
        isSeen = seen;
    }

    public String getSenderId() {
        return senderId;
    }

    public String getReceiverID() {
        return receiverID;
    }

    public String getMessage() {
        return message;
    }

As you can see I am storing 4 values in the chat object but it is only storing three.

Any Idea or Suggestion why this might be...

It's almost certainly the case that friendId is null. Realtime Database won't store anything for null values. We can't see where you are giving friendId a value, so you'll have to debug why this is.