@Suppress("NOTHING_TO_INLINE")
internal inline fun <K, V> Map<K, V>.unmodifiable(): Map<K, V> = Collections.unmodifiableMap(this)

/** Returns an immutable copy of this. */
@Suppress("UNCHECKED_CAST")
internal fun <T> List<T>.toImmutableList(): List<T> =
  when {
    this.isEmpty() -> emptyList()

    this.size == 1 -> Collections.singletonList(this[0])

            alreadyEncoded = true,
            strict = true,
            unicodeAllowed = true,
          )
      }

    fun build(): HttpUrl {
      @Suppress("UNCHECKED_CAST") // percentDecode returns either List<String?> or List<String>.
      return HttpUrl(
        scheme = scheme ?: throw IllegalStateException("scheme == null"),
        username = encodedUsername.percentDecode(),