How to add TCPClient classname in Jmeter

In TCP sampler in jMeter, while simulating with multiple users, what we need to fill in ‘TCPClient classname’? Which class name, I can use? From where this class I will get or how can I create?

https://wiki.apache.org/jmeter/UserManual/Reference/TcpSampler Bottom of the page. It’s optional, and there is a default.