private FieldToRowDataConverter wrapIntoNullableConverter(FieldToRowDataConverter converter) {
        return origStr -> {
            if (StringUtils.isBlank(origStr)) {
                return null;
            }

            return converter.convert(origStr);
        };
    }
Creates a runtime converter which assuming input object is not null.
inlong-sort/sort-formats/format-rowdata/format-rowdata-json/src/main/java/org/apache/inlong/sort/formats/json/FieldToRowDataConverters.java