class CSVFormat implements Serializable {

    public CSVFormat withNullString(final String nullString) {
        return new CSVFormat(delimiter, quoteChar, quotePolicy, commentStart, escape,
                ignoreSurroundingSpaces, ignoreEmptyLines, recordSeparator, nullString, header, skipHeaderRecord);
    }

      CSVFormat(final char delimiter, final Character quoteChar,
            final Quote quotePolicy, final Character commentStart,
            final Character escape, final boolean ignoreSurroundingSpaces,
            final boolean ignoreEmptyLines, final String recordSeparator,
            final String nullString, final String[] header, boolean skipHeaderRecord);

}