in app/com/gu/floodgate/contentsource/ContentSource.scala [66:76]
def reindexEndpointWithDateParams(dateParameters: DateParameters): String = {
def param(key: String, value: Option[String]): Option[String] = value.map(v => s"$key=$v")
val paramFrom = param("from", dateParameters.from map (_.toString))
val paramTo = param("to", dateParameters.to map (_.toString))
val queryString: String = Seq(paramFrom, paramTo).flatten.mkString("&")
val urlSeparator = if (reindexEndpoint contains "?") "&" else "?"
s"$reindexEndpoint$urlSeparator$queryString"
}