If I'm not mistaken JCache would originally have been included in Java EE
7, but just missed the boat and went final a little while after EE 7. So
you could perhaps say that for EE 8 the spec had all the time in the world,
since it was mostly ready before EE 8 even started.
Yet, I don't see much activity regarding JCache and Java EE 8.
If I understood correctly what mostly needs to be done still is the EE
integration. But that too actually seems largely done already.