If I have an array in my document and I wanted to know only the size of the array rather than actual array or to get the top 3 or top 10 rather than full array. I was able to use the pipeline commands slice and size in the mongo cli. But when i use the same in the mongo source connector configuration i don't see any data in the kafka topic. 

Interestingly i don't see any error or issue and I also see something like this in the logs which usually confirms data is published to the topic.

Finished commitOffsets successfully in 3 ms.

Can you please confirm what's the valid pipeline configuration to achieve the above scenario. Thanks in advance.