String extractDynamicIndexPatternStr(String index) {
            int start = index.indexOf("{");
            int end = index.lastIndexOf("}");
            return index.substring(start, end + 1);
        }
Extract dynamic index pattern string 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