docs: private ByteBuffer signPacket(ByteBuffer packet) {
          final byte[] signature = sign(password, (ByteBuffer) ByteBuffer.allocate(packet.remaining() + username.length)
                  .put(username)
                  .put(packet)
                  .flip());
          return (ByteBuffer) ByteBuffer.allocate(BUFFER_SIZE)
                  .putShort((short) TYPE_SIGN_SHA256)
                  .putShort((short) (username.length + SIGNATURE_LEN))
                  .put(signature)
                  .put(username)
                  .put((ByteBuffer) packet.flip())
                  .flip();
      }