The upcoming Android Studio runs in a JVM but has classes from Android and that confused OkHttp!

 *  Fix: Include the header `Accept: text/event-stream` for SSE calls. This header is not added if
    the request already contains an `Accept` header.

 *  Fix: Don't crash with a `NullPointerException` if a server sends a close while we're sending a
    ping. OkHttp had a race condition bug.


## Version 4.6.0

_2020-04-28_

    val derReader = DerReader(buffer)

    derReader.read("test") { header ->
      assertThat(header.tag).isEqualTo(2L)
      assertThat(header.tagClass).isEqualTo(DerHeader.TAG_CLASS_CONTEXT_SPECIFIC)
      assertThat(header.length).isEqualTo(7L)

      derReader.read("test") { header ->
        assertThat(header.tag).isEqualTo(3L)
        assertThat(header.tagClass).isEqualTo(DerHeader.TAG_CLASS_APPLICATION)

      // Read the header.
      val header = Buffer()
      fileOperator.read(0, header, FILE_HEADER_SIZE)
      val prefix = header.readByteString(PREFIX_CLEAN.size.toLong())
      if (prefix != PREFIX_CLEAN) throw IOException("unreadable cache file")
      val upstreamSize = header.readLong()
      val metadataSize = header.readLong()

      // Read the metadata.

  for (i in 0 until length) {
    val c = this[i]
    // 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
    }

        "custom-foo",
        "custom-header",
        "custom-bar",
        "custom-header",
        "custom-baz",
        "custom-header",
      )
    bytesIn.writeByte(0x40) // Literal indexed
    bytesIn.writeByte(0x0a) // Literal name (len = 10)
    bytesIn.writeUtf8("custom-foo")
    bytesIn.writeByte(0x0d) // Literal value (len = 13)
    bytesIn.writeUtf8("custom-header")
    bytesIn.writeByte(0x40) // Literal indexed

  val clientTestRule = OkHttpClientTestRule()
  private lateinit var server: MockWebServer
  private var client = clientTestRule.newClient()
  private val callback = RecordingCallback()

  @BeforeEach
  fun setUp(server: MockWebServer) {
    this.server = server
  }

  @Test
  fun applicationInterceptorsCanShortCircuitResponses() {
    server.shutdown() // Accept no connections.
    val request =
      Request.Builder()

      override fun matches(header: DerHeader): Boolean = true

      override fun fromDer(reader: DerReader): AnyValue {
        reader.read("ANY") { header ->
          val bytes = reader.readUnknown()
          return AnyValue(
            tagClass = header.tagClass,
            tag = header.tag,
            constructed = header.constructed,
            length = header.length,
            bytes = bytes,

 */
class Http2Reader(
  /** Creates a frame reader with max header table size of 4096. */
  private val source: BufferedSource,
  private val client: Boolean,
) : Closeable {
  private val continuation: ContinuationSource = ContinuationSource(this.source)
  private val hpackReader: Hpack.Reader =
    Hpack.Reader(
      source = continuation,
      headerTableSizeSetting = 4096,
    )

    open fun url(url: URL) = url(url.toString().toHttpUrl())

    /**
     * Sets the header named [name] to [value]. If this request already has any headers
     * with that name, they are all replaced.
     */
    open fun header(
      name: String,
      value: String,
    ) = commonHeader(name, value)

    /**
     * Adds a header with [name] and [value]. Prefer this method for multiply-valued
     * headers like "Cookie".

      builder.header("", "Value")
    }
    assertFailsWith<IllegalArgumentException> {
      builder.addHeader("", "Value")
    }
  }

  @Test
  fun headerAllowsTabOnlyInValues() {
    val builder = Request.Builder()
    builder.header("key", "sample\tvalue")
    assertFailsWith<IllegalArgumentException> {
      builder.header("sample\tkey", "value")
    }
  }