null, "" -> null
      else -> protocol
    }
  }

  override fun configureTlsExtensions(
    sslSocket: SSLSocket,
    hostname: String?,
    protocols: List<Protocol>,
  ) {
    // No TLS extensions if the socket class is custom.
    if (matchesSocket(sslSocket)) {
      val bcSocket = sslSocket as BCSSLSocket

      val sslParameters = bcSocket.parameters

   * Returns true if this connection can carry a stream allocation to `address`. If non-null
   * `route` is the resolved route for a connection.
   */
  internal fun isEligible(
    address: Address,
    routes: List<Route>?,
  ): Boolean {
    lock.assertHeld()

    // If this connection is not accepting new exchanges, we're done.
    if (calls.size >= allocationLimit || noNewExchanges) return false

  val headers: List<String>? by option("-H", "--header", help = "Custom header to pass to server").multiple()

  val userAgent: String by option("-A", "--user-agent", help = "User-Agent to send to server").default(NAME + "/" + versionString())

  val connectTimeout: Int by option(
    "--connect-timeout",
    help = "Maximum time allowed for connection (seconds)",
  ).int().default(DEFAULT_TIMEOUT)

 *  Fix: Don't crash when the URL hostname contains an underscore on Android.
 *  Fix: Change HTTP/2 to use a daemon thread for its socket reader. If you've ever seen a command
    line application hang after all of the work is done, it may be due to a non-daemon thread like
    this one.
 *  New: Include suppressed exceptions when all routes to a target service fail.


## Version 4.4.1

      .isEqualTo(generalNameDnsName to "example.com")
    assertThat(CertificateAdapters.generalName.toDer(generalNameDnsName to "example.com"))
      .isEqualTo(bytes)
  }

  @Test fun `extension with type hint for basic constraints`() {
    val extension =
      Extension(
        BASIC_CONSTRAINTS,
        false,
        BasicConstraints(true, 4),
      )

          host: InetAddress,
          port: Int,
        ): Socket? = null

        override fun createSocket(
          address: InetAddress,
          port: Int,
          localAddress: InetAddress,
          localPort: Int,
        ): Socket? = null

        override fun createSocket(
          host: String,
          port: Int,
        ): Socket? = null

    printEvent("callEnd");
  }

  @Override public void dnsStart(Call call, String domainName) {
    printEvent("dnsStart");
  }

  @Override public void dnsEnd(Call call, String domainName, List<InetAddress> inetAddressList) {
    printEvent("dnsEnd");
  }

  ...
}
```

We make a couple calls:

```java
Request request = new Request.Builder()

  }

  private fun String.requiresEncode(
    pos: Int,
    limit: Int,
  ): Boolean {
    for (i in pos until limit) {
      if (this[i].code >= INITIAL_N) return true
    }
    return false
  }

  private fun String.codePoints(
    pos: Int,
    limit: Int,
  ): List<Int> {
    val result = mutableListOf<Int>()
    var i = pos
    while (i < limit) {
      val c = this[i]

    if (e != null) {
      eventListener.callFailed(this, result!!)
    } else {
      eventListener.callEnd(this)
    }
    return result
  }

  /**
   * Remove this call from the connection's list of allocations. Returns a socket that the caller
   * should close.
   */
  internal fun releaseConnectionNoEvents(): Socket? {
    val connection = this.connection!!
    connection.lock.assertHeld()

    // TODO make exception message escape non-printable characters
  }

  @Test
  fun parseDoesNotTrimOtherWhitespaceCharacters() {
    // Whitespace characters list from Google's Guava team: http://goo.gl/IcR9RD
    // line tabulation
    assertThat(parse("http://h/\u000b").encodedPath).isEqualTo("/%0B")
    // information separator 4
    assertThat(parse("http://h/\u001c").encodedPath).isEqualTo("/%1C")