TYPE_SETTINGS -> readSettings(handler, length, flags, streamId)
      TYPE_PUSH_PROMISE -> readPushPromise(handler, length, flags, streamId)
      TYPE_PING -> readPing(handler, length, flags, streamId)
      TYPE_GOAWAY -> readGoAway(handler, length, flags, streamId)
      TYPE_WINDOW_UPDATE -> readWindowUpdate(handler, length, flags, streamId)
      else -> source.skip(length.toLong()) // Implementations MUST discard frames of unknown types.
    }