protected JdbcSerializationConverter wrapIntoNullableExternalConverter(
            JdbcSerializationConverter jdbcSerializationConverter, LogicalType type) {
        return (val, index, statement) -> {
            if (val == null
                    || val.isNullAt(index)
                    || LogicalTypeRoot.NULL.equals(type.getTypeRoot())) {
                // typeInformationToSqlType don't support TIMESTAMP_WITH_LOCAL_TIME_ZONE 2014
                int sqlType = 2014;
                if (type.getTypeRoot() != LogicalTypeRoot.TIMESTAMP_WITH_LOCAL_TIME_ZONE) {
                    sqlType = JdbcTypeUtil.typeInformationToSqlType(
                            TypeConversions.fromDataTypeToLegacyInfo(
                                    TypeConversions.fromLogicalToDataType(type)));
                }
                statement.setNull(index, sqlType);
            } else {
                jdbcSerializationConverter.serialize(val, index, statement);
            }
        };
    }
Create a nullable JDBC f{@link JdbcSerializationConverter} from given sql type.
inlong-sort/sort-flink/sort-flink-v1.13/sort-connectors/jdbc/src/main/java/org/apache/inlong/sort/jdbc/converter/AbstractJdbcRowConverter.java