Eclipse content assist and project natures

Well... I took till 4 A.M. but I found the problem.
In eclipse with JBoss Tools plug-ins installed I want to edit a .jsp page with editor of jboss tools. And the content asist do not work for ELs. For example if you have something like this

<h:outputText value="#{...}" ...


you expect the content assist to work inside the braces to show you for example your beans etc.
But it didn't work. After searching and searching, deleting the whole workspace and setting it up again, and lots of other crazy trial and errors, I realized that it is a project specific problem i.e. the content assist works in other projects.
After comparing the .project files in two projects I see the following lines are missing in my .project file in natures section:

<natures>

...

<nature>org.jboss.tools.jsf.jsfnature</nature>

...

</natures>