presto-main/src/main/java/io/prestosql/sql/planner/EqualityInference.java/EqualityInference/makeEqualitySets
class EqualityInference:    private static Multimap<Expression, Expression> makeEqualitySets(DisjointSet<Expression> equalities)
    {
        ImmutableSetMultimap.Builder<Expression, Expression> builder = ImmutableSetMultimap.builder();
        for (Set<Expression> equalityGroup : equalities.getEquivalentClasses()) {
            if (!equalityGroup.isEmpty()) {
                builder.putAll(CANONICAL_ORDERING.min(equalityGroup), equalityGroup);
            }
        }
        return builder.build();
    }