koltin 如何使用Jackson的ObjectMapper()获取json中的值

fun getObjectMapper(): ObjectMapper {
    return ObjectMapper().registerModule(
      JavaTimeModule().addSerializer(
        LocalDateTime::class, LocalDateTimeSerializer(DateTimeFormatter.ISO_LOCAL_DATE_TIME)
      ).addSerializer(
        ZonedDateTime::class, ZonedDateTimeSerializer(DateTimeFormatter.ISO_OFFSET_DATE_TIME)
      ).addSerializer(YearMonth::class, YearMonthSerializer(DateTimeFormatter.ofPattern("yyyy-MM")))
    ).configure(JsonParser.Feature.ALLOW_UNQUOTED_FIELD_NAMES, true)
  }

inline fun <reified T> ObjectMapper.objectToMap(obj: T): Map<String, Any> =
  this.readValue(this.writeValueAsString(obj), object : com.fasterxml.jackson.core.type.TypeReference<Map<String, Any>>() {})

fun outputPdfFile(bill: Any): File {
    val jsonNode= getObjectMapper().objectToMap(bill)
    val customerName = BillingStackConfig.getConfig().fastoneBilling.customer.name
    return Path.of(
      PathConst.OUTPUT_PATH,
      PathConst.BILL_FOLDER,
      jsonNode["billingCycle"].toString(),
      "$customerName-${jsonNode.get("billingCycle")}-bill.pdf"
    ).toFile()
  }