Integrate my custom mediator with WSO2 ESB log4j

Integrate my custom mediator with WSO2 ESB log4j

I am writing my own custom mediator. In my custom mediator, I use log4j to
log the process..
But I am facing difficulties now when deploy the custom mediator in WSO2.

What I want is the log in my custom mediator will be written in the
"wso2carbon.log". But unfortunately I still have no clue how to do that.
Do I need to configure the log4j.properties here? or do I need to
implement or extends something in my custom mediator?

Thanks :)