Expected behavior

        ByteBuf haystack = Unpooled.copiedBuffer("+PONG\r\n", CharsetUtil.UTF_8);
        ByteBuf needle = Unpooled.copiedBuffer("\r\n", CharsetUtil.UTF_8);
        haystack.readByte();

        int index = ByteBufUtil.indexOf(needle ,haystack);

        System.out.println(index);

expected result is 5.

Actual behavior

actual result is 4.

Steps to reproduce

Minimal yet complete reproducer code (or URL to code)

Netty version

4.1.73.Final-SNAPSHOT

JVM version (e.g. java -version)

openjdk version "11.0.13" 2021-10-19
OpenJDK Runtime Environment (build 11.0.13+8-Ubuntu-0ubuntu1.21.10)
OpenJDK 64-Bit Server VM (build 11.0.13+8-Ubuntu-0ubuntu1.21.10, mixed mode, sharing)

OS version (e.g. uname -a)

Linux XPS-13-9310 5.13.0-22-generic #22-Ubuntu SMP Fri Nov 5 13:21:36 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux