ClassCastException thrown if you have iteratee with projection to a field that have different types stored in mongo and locally.

If you have record with BsonRecord as subrecord and store there fields that have different representation than in mongo (eg java.util.Calendar or joda DateTime in field and get java.util.Date from mongo driver) than you will have class cast exception when trying to use 
the value got from Iter.Item.

Small code example: (same in pull request test case) https://gist.github.com/eiennohito/5053813