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
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
Verify that all the keys marked as required are present.
 @api private
 @raise RequiredAttribute if a required attribute is missing
 @return [void]