src/main/java/com/conveyal/gtfs/loader/DateField.java
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);
        }
    }
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);
        }
    }
DateField specific method to set a statement parameter from a {@link LocalDate}.