presto-main/src/main/java/io/prestosql/sql/planner/optimizations/StreamPropertyDerivations.java/StreamPropertyDerivations/isExactlyPartitionedOn
class StreamPropertyDerivations:        public boolean isExactlyPartitionedOn(Iterable<Symbol> columns)
        {
            return partitioningColumns.isPresent() && columns.equals(ImmutableList.copyOf(partitioningColumns.get()));
        }