…gen already exists but is not a source folder. Convert to a source folder or rename it [closed]

1. Right click on the project and go to "Properties"
2. Select "Java Build Path" on the left
3. Open "Source" tab
4. Click "Add Folder..."
5. Check "gen" folder and click Ok

http://stackoverflow.com/questions/6185600/android-fbreaderj-gen-already-exists-but-is-not-a-source-folder-convert-to-a-s