def expand
      unless @expanded
        resources.values.each(&:apply_resource_type)
        resources.values.each(&:apply_traits)
        inline_reference SchemaReference, schemas, @children
        @expanded = true
      end
    end
def expand
      unless @expanded
        resources.values.each(&:apply_resource_type)
        resources.values.each(&:apply_traits)
        inline_reference SchemaReference, schemas, @children
        @expanded = true
      end
    end
Applies resource types and traits, and inlines schemas.  It should be called
 before documentation is generated.