Q. Eclipse: Create a linked folder
A. I'm not sure how to do it in the GUI but this worked me.
Close your project.
Add it to your .classpath file (in the root folder of your project)
<?xml version="1.0" encoding="UTF-8"?>
<classpathentry kind="src" path="mylinkedfolder"/>
Add it to your .project file (in the root folder of your project)
Open your project and refresh (F5) your folders.