Double brace initialisation (anonymous inner class) with diamond operator

Question

I am wondering why the second map declaration (using the diamond operator) does not compile when the first one does. Compilation error:

error: cannot

Answer 1

This feature is part of Project Coin 2 and will be avalaible in Java 9 coming September 22 of 2016.

It's call Allowing the diamond syntax with some anonymous class constructors.

Link.