code: public Set<NewGTFSError> setParameter (PreparedStatement preparedStatement, int oneBasedIndex, LocalDate localDate) {
          try {
              if (localDate == null) setNull(preparedStatement, oneBasedIndex);
              else preparedStatement.setString(oneBasedIndex, localDate.format(GTFS_DATE_FORMATTER));
              return Collections.EMPTY_SET;
          } catch (Exception e) {
              throw new StorageException(e);
          }
      }
docs: DateField specific method to set a statement parameter from a {@link LocalDate}.