legacyAggregateToStream method
Old version to be used on MongoDb versions prior to 3.6
Implementation
Stream<Map<String, dynamic>> legacyAggregateToStream(List pipeline,
{Map<String, dynamic> cursorOptions = const {},
bool allowDiskUse = false}) {
return AggregateCursor(db, this, pipeline, cursorOptions, allowDiskUse)
.stream;
}