code: public static BatchCSVRecord fromWritables(List<List<Writable>> batch) {
          List <SingleCSVRecord> records = new ArrayList<>(batch.size());
          for(List<Writable> list : batch) {
              List<String> add = new ArrayList<>(list.size());
              for(Writable writable : list) {
                  add.add(writable.toString());
              }
              records.add(new SingleCSVRecord(add));
          }
  
          return BatchCSVRecord.builder().records(records).build();
      }
docs: Create a batch csv record
  from a list of writables.
  @param batch
  @return