Currently the ReducerStream uses a StreamComparator to determine whether tuples are equal. StreamEqualitors are a simplified version of a comparator in that they do not require a sort to be provided. Using the function getStreamSort we are still able to validate the incoming stream's sort and pass that on up to any parent stream which might require it.
This will simplify the use of the ReducerStream in join scenarios where the reducer is used to find like records. Such a scenario exists with Inner/Outer JoinStream, ComplementStream, and [Outer]HashJoinStreams.