The new behavior strips invalid characters like `"` and `{` from the hostname before converting.

 *  Fix: Undo a performance regression introduced in OkHttp 4.0 caused by differences in behavior
    between Kotlin's `assert()` and Java's `assert()`. (Kotlin always evaluates the argument; Java
    only does when assertions are enabled.)

import okhttp3.ResponseBody
import okio.BufferedSource

class RealResponseBody(
  /**
   * Use a string to avoid parsing the content type until needed. This also defers problems caused
   * by malformed content types.
   */
  private val contentTypeString: String?,
  private val contentLength: Long,
  private val source: BufferedSource,
) : ResponseBody() {

      }
    }

    return null
  }

  private fun <E : IOException?> timeoutExit(cause: E): E {
    if (timeoutEarlyExit) return cause
    if (!timeout.exit()) return cause

    val e = InterruptedIOException("timeout")
    if (cause != null) e.initCause(cause)
    @Suppress("UNCHECKED_CAST") // E is either IOException or IOException?
    return e as E
  }

  /**

  fun sendFrame(): Http2Writer {
    outFrames.add(OutFrame(frameCount++, bytesOut.size, false))
    return writer
  }

  /**
   * Shortens the last frame from its original length to `length`. This will cause the peer to
   * close the socket as soon as this frame has been written; otherwise the peer stays open until
   * explicitly closed.
   */
  fun truncateLastFrame(length: Int): Http2Writer {

  private val data = Buffer()
  private val random = Random(0)

  /**
   * Check all data as verified inside of the test. We do this in an AfterEachCallback so that
   * exceptions thrown from the test do not cause this check to fail.
   */
  @RegisterExtension
  val noDataLeftBehind =
    AfterEachCallback { context: ExtensionContext ->
      if (context.executionException.isPresent) return@AfterEachCallback

    // The WHATWG Host parsing rules accepts some character codes which are invalid by
    // definition for OkHttp's host header checks (and the WHATWG Host syntax definition). Here
    // we rule out characters that would cause problems in host headers.
    if (c <= '\u001f' || c >= '\u007f') {
      return true
    }
    // Check for the characters mentioned in the WHATWG Host parsing spec:

    )
    inputStream.close()
    assertContent("ABCDEFGHIJKLMNOPQRSTUVWXYZ", getResponse(newRequest("/")))
  }

  /**
   * We've had a bug where we forget the HTTP response when we see response code 401. This causes a
   * new HTTP request to be issued for every call into the URLConnection.
   */
  @Test
  fun unauthorizedResponseHandling() {
    val mockResponse =
      MockResponse(

    bug where shutdown HTTP/2 connections were considered usable. This caused
    infinite loops when calls attempted to recover.


## Version 3.4.1

_2016-07-10_

 *  **Fix a major bug in encoding HTTP headers.** In 3.4.0 and 3.4.0-RC1 OkHttp
    had an off-by-one bug in our HPACK encoder. This bug could have caused the
    wrong headers to be emitted after a sequence of HTTP/2 requests! Everyone

    } catch (e: IllegalAccessException) {
      throw AssertionError(e)
    } catch (e: InvocationTargetException) {
      // https://github.com/square/okhttp/issues/5587
      val cause = e.cause
      when {
        cause is NullPointerException && cause.message == "ssl == null" -> null
        else -> throw AssertionError(e)
      }
    }
  }

  companion object {
    val playProviderFactory: DeferredSocketAdapter.Factory =

`checkstyle-result.xml` file.

Some general advice

- Don’t change public API lightly, avoid if possible, and include your reasoning in the PR if essential.  It causes pain for developers who use OkHttp and sometimes runtime errors.
- Favour a working external library if appropriate.  There are many examples of OkHttp libraries that can sit on top or hook in via existing APIs.