Sample login app for Android Java will not compile

I am running Android Studio 3.1.1 on an Ubuntu linux machine. I have downloaded and installed backendless-4.5.1.jar. From the backendless console I downloaded the sample “login” app. When I try to run the sample code in Android Studio I get the following error message: “Compilation failed”. The java compiler error log says the problem is in The specific compiler error message is: “error: cannot find symbol class AsyncCallback.” In line 91 of RegisterActivity the code reads: “Backendless.UserService.register(user, new AsyncCallback<BackendlessUser>();” The AsyncCallback portion of this line of code is flagged in red. So, what can I do by myself to correct this situation?

Thank you in advance. I am a newbie and still earning the product.

I added the following import and the problem went away

import com.backendless.async.callback.AsyncCallback;

Can someone at Backendless please update the sample app? Thank you.

Hi, Russ. Thanks for your comment. We have fixed this, and the changes will be applied on the next production update.