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