public static RowFieldConverter createNullableRowFieldConverter(LogicalType fieldType) {
        final RowFieldConverter fieldConverter = createRowFieldConverter(fieldType);
        return (row, pos) -> {
            if (row.isNullAt(pos)) {
                return null;
            }
            return fieldConverter.convert(row, pos);
        };
    }
Runtime converter that converts objects of Flink Table & SQL internal data structures to
corresponding {@link Object}s.
inlong-sdk/transform-sdk/src/main/java/org/apache/inlong/sdk/transform/utils/RowToFieldDataUtils.java