def valid_sets
      sets = @site.config["defaults"]
      return [] unless sets.is_a?(Array)

      sets.map do |set|
        if valid?(set)
          ensure_time!(update_deprecated_types(set))
        else
          Jekyll.logger.warn "Defaults:", "An invalid front-matter default set was found:"
          Jekyll.logger.warn set.to_s
          nil
        end
      end.compact
    end
def valid_sets
      sets = @site.config["defaults"]
      return [] unless sets.is_a?(Array)

      sets.map do |set|
        if valid?(set)
          ensure_time!(update_deprecated_types(set))
        else
          Jekyll.logger.warn "Defaults:", "An invalid front-matter default set was found:"
          Jekyll.logger.warn set.to_s
          nil
        end
      end.compact
    end
Returns a list of valid sets

 This is not cached to allow plugins to modify the configuration
 and have their changes take effect

 Returns an array of hashes