Symmetrically, interceptors can rewrite response headers and transform the response body. This is generally more dangerous than rewriting request headers because it may violate the webserver's expectations!

If you're in a tricky situation and prepared to deal with the consequences, rewriting response headers is a powerful way to work around problems. For example, you can fix a server's misconfigured `Cache-Control` response header to enable better response caching:

      .isEqualTo("<< 0x00000003     0 HEADERS       END_STREAM")
    assertThat(frameLog(true, 3, 0, TYPE_DATA, 0x1))
      .isEqualTo("<< 0x00000003     0 DATA          END_STREAM")
  }

  @Test
  fun flagOverlapOn0x4() {
    assertThat(frameLog(true, 3, 10000, TYPE_HEADERS, 0x4))
      .isEqualTo("<< 0x00000003 10000 HEADERS       END_HEADERS")

    )
  }

  @Test fun pushPromise() {
    val expectedPromisedStreamId = 11
    val pushPromise =
      listOf(
        Header(Header.TARGET_METHOD, "GET"),
        Header(Header.TARGET_SCHEME, "https"),
        Header(Header.TARGET_AUTHORITY, "squareup.com"),
        Header(Header.TARGET_PATH, "/"),
      )

    // Write the push promise frame, specifying the associated stream ID.

 */
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,
    )

    assertThat(cacheControl.toString()).isEqualTo(header)
  }

  @Test
  @Throws(Exception::class)
  fun parseIgnoreCacheControlExtensions() {
    // Example from http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.9.6
    val header = "private, community=\"UCI\""
    val cacheControl =
      parse(
        Headers
          .Builder()
          .set("Cache-Control", header)
          .build(),
      )

              println("onResponseStarted ${info.headers.asMap} ${info.negotiatedProtocol}")
              request.read(ByteBuffer.allocateDirect(4096 * 8))
            }

            override fun onReadCompleted(
              request: UrlRequest,
              info: UrlResponseInfo,
              byteBuffer: ByteBuffer,
            ) {
              println("onReadCompleted ${info.headers.asMap}")
              byteBuffer.flip()

    /**
     * CORS header for specifying allowed headers.
     */
    protected static final String ACCESS_CONTROL_ALLOW_HEADERS = "Access-Control-Allow-Headers";

    /**
     * CORS header for specifying allowed HTTP methods.
     */
    protected static final String ACCESS_CONTROL_ALLOW_METHODS = "Access-Control-Allow-Methods";

    /**
     * CORS header for allowing private network access.
     */

        .build();

    try (Response response = client.newCall(request).execute()) {
      if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);

      Headers responseHeaders = response.headers();
      for (int i = 0; i < responseHeaders.size(); i++) {
        System.out.println(responseHeaders.name(i) + ": " + responseHeaders.value(i));
      }

      System.out.println(response.body().string());

    assertThat(response.protocol).isEqualTo(protocol)
    val logs = testLogHandler.takeAll()
    assertThat(firstFrame(logs, "HEADERS")!!, "header logged")
      .contains("HEADERS       END_HEADERS")
    // While MockWebServer waits to read the client's HEADERS frame before sending the response, it
    // doesn't wait to read the client's DATA frame and may send a DATA frame before the client

  return millis.toInt()
}

internal fun List<Header>.toHeaders(): Headers {
  val builder = Headers.Builder()
  for ((name, value) in this) {
    builder.addLenient(name.utf8(), value.utf8())
  }
  return builder.build()
}

internal fun Headers.toHeaderList(): List<Header> =
  (0 until size).map {
    Header(name(it), value(it))
  }