assertThat(expected.message)
        .isEqualTo("Client-sent frames must be masked.")
    }
  }

  @Test fun serverSentFramesMustNotBeMasked() {
    data.write("8180".decodeHex())
    assertFailsWith<ProtocolException> {
      clientReader.processNextFrame()
    }.also { expected ->
      assertThat(expected.message)
        .isEqualTo("Server-sent frames must not be masked.")
    }
  }

```
$ adb shell setprop log.tag.okhttp.Http2 DEBUG
$ adb shell setprop log.tag.okhttp.TaskRunner DEBUG
$ adb logcat '*:E' 'okhttp.Http2:D' 'okhttp.TaskRunner:D'
```

### HTTP/2 Frame Logging

This logs inbound (`<<`) and outbound (`>>`) frames for HTTP/2 connections.

```
[2020-01-01 00:00:00] >> CONNECTION 505249202a20485454502f322e300d0a0d0a534d0d0a0d0a
[2020-01-01 00:00:00] >> 0x00000000     6 SETTINGS

The frame size <code>$24-8</code> states that the function has a 24-byte frame
and is called with 8 bytes of argument, which live on the caller's frame.
If <code>NOSPLIT</code> is not specified for the <code>TEXT</code>,
the argument size must be provided.
For assembly functions with Go prototypes, <code>go</code> <code>vet</code> will check that the
argument size is correct.
</p>

<p>

min-media-query !default;\n\n// Generate enable or disable classes. Possibilities: false, \"enable\" or \"disable\"\n$rfs-class: false !default;\n\n// 1 rem = $rfs-rem-value px\n$rfs-rem-value: 16 !default;\n\n// Safari iframe resize bug: https://github.com/twbs/rfs/issues/14\n$rfs-safari-iframe-resize-bug-fix: false !default;\n\n// Disable RFS by setting $enable-rfs to false\n$enable-rfs: true !default;\n\n// Cache $rfs-base-value unit\n$rfs-base-value-unit: unit($rfs-base-value);\n\n@function divide($dividend,...

 *  Fix: MockWebServer explicitly closes sockets. (On some Android releases,
    closing the input stream and output stream of a socket is not sufficient.
 *  Fix: Buffer outgoing HTTP/2 frames to limit how many outgoing frames are
    created.
 *  Fix: Avoid crashing when cache writing fails due to a full disk.
 *  Fix: Improve caching of private responses.
 *  Fix: Update cache-by-default response codes.

    assertThat(webSocket.close(1000, null)).isFalse()
  }

  /**
   * There's no read timeout when reading the first byte of a new frame. But as soon as we start
   * reading a frame we enable the read timeout. In this test we have the server returning the first
   * byte of a frame but no more frames.
   */
  @Test
  fun readTimeoutAppliesWithinFrames() {
    webServer.dispatcher =
      object : Dispatcher() {

  /** Byte 0 reserved flag 3. Must be 0 unless negotiated otherwise. */
  internal const val B0_FLAG_RSV3 = 16

  /** Byte 0 mask for the frame opcode. */
  internal const val B0_MASK_OPCODE = 15

  /** Flag in the opcode which indicates a control frame. */
  internal const val OPCODE_FLAG_CONTROL = 8

  /**
   * Byte 1 flag for whether the payload data is masked.
   *
   * If this flag is set, the next four

ay:inline-flex!important}}.embed-responsive{position:relative;display:block;width:100%;padding:0;overflow:hidden}.embed-responsive::before{display:block;content:""}.embed-responsive .embed-responsive-item,.embed-responsive embed,.embed-responsive iframe,.embed-responsive object,.embed-responsive video{position:absolute;top:0;bottom:0;left:0;width:100%;height:100%;border:0}.embed-responsive-21by9::before{padding-top:42.857143%}.embed-responsive-16by9::before{padding-top:56.25%}.embed-responsive-4...

    } finally {
      service.shutdown();
    }
    assertThat(holder.count).isEqualTo(ITERATION_COUNT);
    for (int length : completeLengthChecks) {
      // Verify that at max depth, less than one stack frame per submitted task was consumed
      assertThat(length - baseStackDepth).isLessThan(DIRECT_EXECUTIONS_PER_THREAD / 2);
    }
  }

  @SuppressWarnings("ObjectToString") // Intended behavior

      direction,
      streamId,
      length,
      formattedType,
      formattedFlags,
    )
  }

  /**
   * Returns a human-readable representation of a `WINDOW_UPDATE` frame. This frame includes the
   * window size increment instead of flags.
   */
  fun frameLogWindowUpdate(
    inbound: Boolean,
    streamId: Int,
    length: Int,
    windowSizeIncrement: Long,
  ): String {