How to have an array as a value on MongoDB Output step ?

Hii,

I am new to Kettle but I think this problem should be relatively simple. Still, I haven't been able to figure it out yet.
I have a TABLE INPUT where I have the following fields..

Id, Name, Interests

I am using the MongoDB Output step and have so far been able to get the following structure for the field interests which is originally a CSV value in the table

{
"interests" : {
"interest" : "singing",
"interest" : "dancing"
}
}

But What I really want is an array with Key as Interests .. like..

{
"interests" : ["singing", "dancing"]
}

How do we do that using Kettle ?

Thanks..