if conf.has_key?('localtime') || conf.has_key?('utc')
          if conf.has_key?('localtime') && conf.has_key?('utc')
            raise Fluent::ConfigError, "both of utc and localtime are specified, use only one of them"
          elsif conf.has_key?('localtime')
            inject_params['localtime'] = Fluent::Config.bool_value(conf['localtime'])