private String extractDateFormat(String index, LogicalTypeRoot logicalType) {
            String format = index.substring(index.indexOf("|") + 1, index.indexOf("}"));
            if ("".equals(format)) {
                format = getDefaultFormat(logicalType);
            }
            return format;
        }
Extract dateTime format by the date format that extracted from index pattern string.
inlong-sort/sort-flink/sort-flink-v1.13/sort-connectors/elasticsearch-base/src/main/java/org/apache/inlong/sort/elasticsearch/table/IndexGeneratorFactory.java