internal fun Headers.commonName(index: Int): String = namesAndValues.getOrNull(index * 2) ?: throw IndexOutOfBoundsException("name[$index]")

internal fun Headers.commonValue(index: Int): String =
  namesAndValues.getOrNull(index * 2 + 1) ?: throw IndexOutOfBoundsException("value[$index]")

internal fun Headers.commonValues(name: String): List<String> {
  var result: MutableList<String>? = null
  for (i in 0 until size) {