This module allows you to declare class attributes in exactly the same way as
object attributes, using class_has() instead of has().
You can use any feature of Moose's attribute declarations, including overriding
a parent's attributes, delegation (handles), and attribute metaclasses, and it
should just work. The one exception is the "required" flag, which is not
allowed for class attributes.
The accessor methods for class attribute may be called on the class directly,
or on objects of that class. Passing a class attribute to the constructor will
not set it.