final String template = """
                {"source":{"index":"__SOURCE_INDEX__","size":__SIZE__},"dest":{"index":"__DEST_INDEX__"}}
                """;
        final FessConfig fessConfig = ComponentUtil.getFessConfig();
        final String source = template //
                .replace("__SOURCE_INDEX__", fromIndex)//
                .replace("__SIZE__", fessConfig.getIndexReindexSize())//

    String INDEX_FILETYPE = "index.filetype";

    /** The key of the configuration. e.g. 100 */
    String INDEX_REINDEX_SIZE = "index.reindex.size";

    /** The key of the configuration. e.g. {"source":{"index":"__SOURCE_INDEX__","size":__SIZE__},"dest":{"index":"__DEST_INDEX__"},"script":{"source":"__SCRIPT_SOURCE__"}} */
    String INDEX_REINDEX_BODY = "index.reindex.body";

    /** The key of the configuration. e.g. adaptive */

image/tiff=tiff\n\
image/jpeg=jpg\n\

# Number of documents to process per reindex operation.
index.reindex.size=100
# Request body template for reindex operations.
index.reindex.body={"source":{"index":"__SOURCE_INDEX__","size":__SIZE__},"dest":{"index":"__DEST_INDEX__"},"script":{"source":"__SCRIPT_SOURCE__"}}
# Requests per second for reindex operations ("adaptive" for auto).
index.reindex.requests_per_second=adaptive