@Override
    public List<String> getFieldNames() {
      if (formatJson) {
        return Collections.singletonList("CoW/MoR");
      }
      return Arrays.asList(WRITE_MERGE_MODE, WRITE_DELETE_MODE, WRITE_UPDATE_MODE);
    }
Collect the summary based on the table's properties.
It could be the version, write mode or compression, etc.
iceberg/iceberg-handler/src/main/java/org/apache/iceberg/metasummary/TablePropertySummary.java