Solve "source folder is not a Java project error" in Eclipse

When we import project from somewhere, Maven sometimes doesn't understand the project as a Java project in Eclipse and shows error as source folder is not a Java project.

Many programmers believes it as a bug because Maven should automatically recognise Java project.

For the time being, if you are facing this issue:

You can try two approaches to solve this:

1. run as

 mvn eclipse : eclipse

2. Change project facets

Right click on Properties

Click on Project Facets

Click check on Java

Click Apply