}

private fun Main.mediaType(): MediaType? {
  val mimeType =
    headers?.let {
      for (header in it) {
        val parts = header.split(':', limit = 2)
        if ("Content-Type".equals(parts[0], ignoreCase = true)) {
          return@let parts[1].trim()
        }
      }
      return@let null
    } ?: "application/x-www-form-urlencoded"

  return mimeType.toMediaTypeOrNull()
}

internal fun <T> readFieldOrNull(
  instance: Any,
  fieldType: Class<T>,
  fieldName: String,
): T? {
  var c: Class<*> = instance.javaClass
  while (c != Any::class.java) {
    try {
      val field = c.getDeclaredField(fieldName)
      field.isAccessible = true
      val value = field.get(instance)
      return if (!fieldType.isInstance(value)) null else fieldType.cast(value)
    } catch (_: NoSuchFieldException) {
    }