public static String contentTypeKey(final ServerWebExchange exchange) {
        return String.join(KEY_JOIN_RULE, dataKey(exchange), CONTENT_TYPEKEY_SUFFIX);
    }
the cache data content type key.

@param exchange the exchange
@return the content type key
shenyu-plugin/shenyu-plugin-cache/shenyu-plugin-cache-handler/src/main/java/org/apache/shenyu/plugin/cache/utils/CacheUtils.java