Getting error at the time of copy

Hi ,
I am trying to deploy this docker-java-sample-webapp into Azure -devops service I am getting the error at the time build image. Could you please help me on that.
<img width="714" alt="capture" src="https://user-images.githubusercontent.com/47966252/53805332-da6ce480-3f6f-11e9-8901-0af5b886815b.PNG">

