presto-parser/src/main/java/io/prestosql/sql/tree/SortItem.java/SortItem/equals
class SortItem:    @Override
    public boolean equals(Object o)
    {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }

        SortItem sortItem = (SortItem) o;
        return Objects.equals(sortKey, sortItem.sortKey) &&
                (ordering == sortItem.ordering) &&
                (nullOrdering == sortItem.nullOrdering);
    }