java.util.ConcurrentModificationException with serializeJson()

Is it necessary to cflock when using serializeJson() on a large struct of
nested array/struct/string data types that is written to by multiple
threads at once?

I just had this exception on newest lucee 4.5 that I haven’t had before.

java.util.ConcurrentModificationException

The cfml code is like
callFunction("/path/to/file", serializeJson(struct));

I put an exclusive lock on it for now and separated it from the function
call.