public static SerializableFunction createKeyExtractor()

in flink-connector-elasticsearch-base/src/main/java/org/apache/flink/connector/elasticsearch/table/KeyExtractor.java [62:77]


    public static SerializableFunction<RowData, String> createKeyExtractor(
            List<LogicalTypeWithIndex> primaryKeyTypesWithIndex, String keyDelimiter) {
        if (!primaryKeyTypesWithIndex.isEmpty()) {
            FieldFormatter[] formatters =
                    primaryKeyTypesWithIndex.stream()
                            .map(
                                    logicalTypeWithIndex ->
                                            toFormatter(
                                                    logicalTypeWithIndex.index,
                                                    logicalTypeWithIndex.logicalType))
                            .toArray(FieldFormatter[]::new);
            return new KeyExtractor(formatters, keyDelimiter);
        } else {
            return (row) -> null;
        }
    }