ConcurrentModificationException

Hi,

I needed to call a connector many times in a row, i created a call activity with iteration (sequential multi-instantiation). After a while it stops working with ConcurrentModificationException, after starting it over again it doesnt stop with the same data, it stops randomly. I started over again and again, always deleting the elements that was already finished, after 7 restarts it finished.

To me it looked like a random error, what causes this error? How to get around this?

As i wrote in the question i get this error, and dont know why, i assumed the bonita engine causes this error, since i dont use HashMap object in my connector.

This is the full error: