OnTrigger - FlowFile is Null

[Manish Gupta 8]

Hi,

In one of our custom processor, I forgot to mention the following check, and 
the error started showing up randomly.

        if (flowFile == null) {
            return;
        }


I am just curious to know, in what situation would onTrigger will get called if 
there is no FlowFile?

Regards,
Manish