throw IOException("FRAME_SIZE_ERROR: $length")
    }
    val type = source.readByte() and 0xff
    val flags = source.readByte() and 0xff
    val streamId = source.readInt() and 0x7fffffff // Ignore reserved bit.
    if (type != TYPE_WINDOW_UPDATE && logger.isLoggable(FINE)) {
      logger.fine(frameLog(true, streamId, length, type, flags))
    }

    if (requireSettings && type != TYPE_SETTINGS) {