def build_source_list_directive(directive)
      source_list = @config.directive_value(directive)

      if source_list != OPT_OUT && source_list && source_list.any?
        normalized_source_list = minify_source_list(directive, source_list)
        [symbol_to_hyphen_case(directive), normalized_source_list].join(" ")
      end
    end
def build_source_list_directive(directive)
      source_list = @config.directive_value(directive)

      if source_list != OPT_OUT && source_list && source_list.any?
        normalized_source_list = minify_source_list(directive, source_list)
        [symbol_to_hyphen_case(directive), normalized_source_list].join(" ")
      end
    end
Private: builds a string that represents one directive in a minified form.

 directive_name - a symbol representing the various ALL_DIRECTIVES

 Returns a string representing a directive.