The RoleId/IsPredefined property of Role schema

> I would like to ask if anyone knows why "RoleId" property is not listed as required.

We tend not to overly constrain implementations when adding new properties. However, in this case, I think it's trivial to make this required.

> If “IsPredefined” is missing, should I assume its implicit value is True?

I could see arguments going either way. The specification calls out this statement: The IsPredefined property for standard roles shall contain the value true. So, I could see that people could come to the conclusion that predefined roles will always have this property.

I'll raise both of these questions for discussion to see if we need to clarify anything.