code: def verify_required!
        @key_metadata.required_properties.each do |key_name|
          next if @source.key?(@key_metadata.get(key_name).source_key)
          raise RequiredAttribute, "#{@parent} requires `#{key_name}`"
        end
      end
docs: Verify that all the keys marked as required are present.
   @api private
   @raise RequiredAttribute if a required attribute is missing
   @return [void]