code: public static List<List<String>> convertWritableInputToString(List<List<Writable>> stringInput,Schema schema) {
          List<List<String>> ret = new ArrayList<>();
          List<List<String>> timeStepAdd = new ArrayList<>();
          for(int j = 0; j < stringInput.size(); j++) {
              List<Writable> record = stringInput.get(j);
              List<String> recordAdd = new ArrayList<>();
              for(int k = 0; k < record.size(); k++) {
                  recordAdd.add(record.get(k).toString());
              }
  
              timeStepAdd.add(recordAdd);
          }
  
  
          return ret;
      }
docs: Convert a string time series to
  the proper writable set based on the schema.
  Note that this does not use arrow.
  This just uses normal writable objects.
  
  @param stringInput the string input
  @param schema the schema to use
  @return the converted records