int byte2 = bytes[index++];
        if (byte2 > (byte) 0xBF
            // Check that 1 <= plane <= 16. Tricky optimized form of:
            // if (byte1 > (byte) 0xF4
            //     || byte1 == (byte) 0xF0 && byte2 < (byte) 0x90
            //     || byte1 == (byte) 0xF4 && byte2 > (byte) 0x8F)
            || (((byte1 << 28) + (byte2 - (byte) 0x90)) >> 30) != 0
            // Third byte trailing-byte test

        new byte[] {
          0x01, (byte) 0xc0, 0x00, 0x00,
          0x00, 0x00, 0x00, 0x00,
          0x00, 0x00, 0x00, 0x00,
          0x00, 0x00, 0x00, 0x00,
          0x14, 0x00, 0x00, 0x00,
          0x00, 0x00, 0x04, 0x00,
          0x00, 0x00, 0x00, 0x14,
          0x00, 0x00, 0x00, 0x18,
          0x28, 0x00, 0x00, 0x00,
          0x00, 0x00, 0x00, 0x00,
          0x02, 0x00, 0x00, 0x00,
          0x00, 0x00, 0x00, 0x00

  public void testCollisionsDueToIncorrectSignExtension() {
    byte[] col1 = new byte[] {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, (byte) 0x80};
    byte[] col2 = new byte[] {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, (byte) 0x81};
    byte[] col3 = new byte[] {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, (byte) 0xff};

    ImmutableSet<HashCode> hashCodes =
        ImmutableSet.of(

  @Test
  fun flagOverlapOn0x4() {
    assertThat(frameLog(true, 3, 10000, TYPE_HEADERS, 0x4))
      .isEqualTo("<< 0x00000003 10000 HEADERS       END_HEADERS")
    assertThat(frameLog(true, 3, 10000, TYPE_CONTINUATION, 0x4))
      .isEqualTo("<< 0x00000003 10000 CONTINUATION  END_HEADERS")
    assertThat(frameLog(true, 4, 10000, TYPE_PUSH_PROMISE, 0x4))
      .isEqualTo("<< 0x00000004 10000 PUSH_PROMISE  END_PUSH_PROMISE")
  }

  @Test

  const val TYPE_SETTINGS = 0x4
  const val TYPE_PUSH_PROMISE = 0x5
  const val TYPE_PING = 0x6
  const val TYPE_GOAWAY = 0x7
  const val TYPE_WINDOW_UPDATE = 0x8
  const val TYPE_CONTINUATION = 0x9

  const val FLAG_NONE = 0x0
  const val FLAG_ACK = 0x1 // Used for settings and ping.
  const val FLAG_END_STREAM = 0x1 // Used for headers and data.
  const val FLAG_END_HEADERS = 0x4 // Used for headers and continuation.