Q:

How to include a JSP file in a Facelets file? 

How can I include a .jsp file into a facelet? 

A:

This is by default not supported.  You need to create a custom component for this.  You can find complete examples in this blog and this answer.  The OmniFaces component library has a reuseable <o:resourceInclude> component for this. 
<html ... xmlns:o="http://omnifaces.org/ui">
...
<o:resourceInclude path="/foo.jsp" />

