void function ( ) { }
called after the last call to combine on a specific instance . enables disposing of the intermediary state . this should be a very fast operation that just disposes unnecessary state if applicable . important : it may not be called if the instance aggregator does not take part in the accumulation phase . it 's caused by the fact that the aggregation may be run in a parallel way and each thread gets a clone of the aggregator . concode_field_sep PlaceHolder placeHolder concode_field_sep void accumulate concode_elem_sep void onCombinationFinished concode_elem_sep void combine concode_elem_sep R aggregate