is there a standard way to set a custom FileOutputCommitter?

[JunYoung Kim]

Hi, 

I want to set my custom (overried) FileOutputCommitter because it provides the 
method named 'rename'. 
This method has a role to move an output dir in temp output to a real output 
dir.

but, it checks output file is existed or not before moving it.
this logic is not proper in my case. 

I want to concatenate it if output file is already existed.

Is this possible? If it it possible, how could I set it properly?

thanks.