presto-jmx/src/main/java/io/prestosql/plugin/jmx/JmxColumnHandle.java/JmxColumnHandle/toString
class JmxColumnHandle:    @Override
    public String toString()
    {
        return toStringHelper(this)
                .add("columnName", columnName)
                .add("columnType", columnType)
                .toString();
    }