presto-main/src/main/java/io/prestosql/sql/planner/planprinter/IoPlanPrinter.java/IoPlanPrinter/toString
class IoPlanPrinter:        @Override
        public String toString()
        {
            return toStringHelper(this)
                    .add("columnName", columnName)
                    .add("typeSignature", type)
                    .add("domain", domain)
                    .toString();
        }