Effective finality requirements for method reference receiver ?

[Srikanth S Adayapalam]

Are there any ? 

0.6.1 - Part C is silent. The words final and capture don't occur there.
But SOTL 4th edition talks about the implicit lambda capturing a variable
and using that as the receiver. Spec should override all other prose - 
right ?
I also see that the mention of implicit lambda is from a pedagogical pov.

BTW, 0.6.1 Part B links to SOTL edition 3 - which is very outdated with 
respect
to the present state of affairs.

I see that javac 8b74 compiles this code fine:

// --
interface I {
        void foo();
}

public class X {
        private void foo() {
                X x = new X();
                x = new X();
                I i = x::foo;
        }
}
 
Thanks in advance for any clarifications.
Srikanth.