create a ManagedBean Foo:
-----------------
@ManagedBean(name = "Foo")
@RequestScoped
public class Foo {

    protected List<String> friends;

    public List<String> getFriends() {
        return friends;
    }

    public void setFriends(List<String> friends) {
        this.friends = friends;
    }
}
------------------
use EL in XHTML and invoke cc at position of "|" -> 'empty' is offered:
${Foo.friends.|}
complete code -> you get ${Foo.friends.empty}
     note that 'empty' gets coloring as EL keyword;
running the application causes error shown in browser:
---------------------
An Error Occurred:
/index.xhtml @12,39 test="${Foo.friends.empty}" Error Parsing: ${Foo.friends.empty}
---------------------

We should not offer keywords as properties in cc and it would be also good candidate for an error message shown in editor if a keyword is used as a property