presto-spi/src/main/java/io/prestosql/spi/connector/GroupingProperty.java/GroupingProperty/toString
class GroupingProperty:    @Override
    public String toString()
    {
        StringBuilder builder = new StringBuilder();
        builder.append("G(");
        builder.append(columns.stream()
                .map(Object::toString)
                .collect(Collectors.joining(", ")));
        builder.append(")");
        return builder.toString();
    }