'CometChat Cannot resolve symbol 'CometChatUserListScreen'

I have been following the tutorial for CometChat. It seems some imports are not working. How to I fix?

tutorial site: https://www.cometchat.com/tutorials/how-to-build-an-android-chat-app-in-java

public class ContactActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_contact);

        CometChatUserListScreen.setItemClickListener(new OnItemClickListener<User>() 
    {
            @Override
            public void OnItemClick(User var, int position) {
                 Intent intent = new 
Intent(ContactsActivity.this,CometChatMessageScreen.class);
                intent.putExtra(StringContract.IntentStrings.UID, var.getUid());
                intent.putExtra(StringContract.IntentStrings.NAME, var.getName());
                intent.putExtra(StringContract.IntentStrings.AVATAR, var.getAvatar());
                intent.putExtra(StringContract.IntentStrings.TYPE, 
CometChatConstants.RECEIVER_TYPE_USER);
                startActivity(intent);
            }
            @Override
            public void OnItemLongClick(User var, int position) {
                super.OnItemLongClick(var, position);
            }
        });
    }
}

screen shot here