this because it only occurs if you have proxy configured and you share a connection pool among
    multiple `OkHttpClient` instances.

    This particularly-subtle bug was caused by us assigning each `OkHttpClient` instance its own
    `NullProxySelector` when an explicit proxy is configured. But we don't share connections when
    the proxy selectors are different. Ugh!


## Version 4.2.0

          a: String,
          b: String,
        ): Int {
          var i = 4
          val limit = minOf(a.length, b.length)
          while (i < limit) {
            val charA = a[i]
            val charB = b[i]
            if (charA != charB) return if (charA < charB) -1 else 1
            i++
          }
          val lengthA = a.length
          val lengthB = b.length

/**
 * A set of tasks that are executed in sequential order.
 *
 * Work within queues is not concurrent. This is equivalent to each queue having a dedicated thread
 * for its work; in practice a set of queues may share a set of threads to save resources.
 */
class TaskQueue internal constructor(
  internal val taskRunner: TaskRunner,
  internal val name: String,
) {
  val lock: ReentrantLock = ReentrantLock()

      verifyHostname(hostname, it)
    }
  }

  /**
   * This is like [toLowerCase] except that it does nothing if this contains any non-ASCII
   * characters. We want to avoid lower casing special chars like U+212A (Kelvin symbol) because
   * they can return ASCII characters that match real hostnames.
   */
  private fun String.asciiToLowercase(): String {
    return when {

      assertThat(expected.message).isEqualTo("Unexpected char 0x20 at 1 in header name: a b")
    }
  }

  @Test
  fun requestHeaderNameWithTabForbidden() {
    assertFailsWith<IllegalArgumentException> {
      Request.Builder().addHeader("a\tb", "c")
    }.also { expected ->
      assertThat(expected.message).isEqualTo("Unexpected char 0x09 at 1 in header name: a\tb")
    }
  }

  @Test

efficiently makes your stuff load faster and saves bandwidth.

OkHttp is an HTTP client that’s efficient by default:

 * HTTP/2 support allows all requests to the same host to share a socket.
 * Connection pooling reduces request latency (if HTTP/2 isn’t available).
 * Transparent GZIP shrinks download sizes.
 * Response caching avoids the network completely for repeat requests.

   * The maximum number of requests for each host to execute concurrently. This limits requests by
   * the URL's host name. Note that concurrent requests to a single IP address may still exceed this
   * limit: multiple hostnames may share an IP address or be routed through the same HTTP proxy.
   *
   * If more than [maxRequestsPerHost] requests are in flight when this is invoked, those requests
   * will remain in flight.
   *

   */
  @get:JvmName("hostOnly") val hostOnly: Boolean,
  /**
   * Returns a string describing whether this cookie is sent for cross-site calls.
   *
   * Two URLs are on the same site if they share a [top private domain][HttpUrl.topPrivateDomain].
   * Otherwise, they are cross-site URLs.
   *
   * When a URL is requested, it may be in the context of another URL.
   *

 * explicitly requested), this also includes that proxy information. For secure connections the
 * address also includes the SSL socket factory, hostname verifier, and certificate pinner.
 *
 * HTTP requests that share the same [Address] may also share the same [Connection].
 */
class Address(
  uriHost: String,
  uriPort: Int,
  /** Returns the service that will be used to resolve IP addresses for hostnames. */
  @get:JvmName("dns") val dns: Dns,

 * prefix are called a 'section'. There are 128 code points per section.
 *
 * Ranges Data (32,612 bytes)
 * ==========================
 *
 * Each entry is 4 bytes, and represents a _range_ of code points that all share a common 14-bit
 * prefix. Entries are sorted by their complete code points.
 *
 * The 4 bytes are named b0, b1, b2 and b3. We also define these supplemental values:
 *
 *  * **b2a**: b2 + 0x80
 *  * **b3a**: b3 + 0x80