public Mono<R> execute(final Mono<R> response, final ServerWebExchange exchange, final Duration duration, final int retryTimes) {
        Retry retrySpec = initFixedBackoff(retryTimes);
        return response.retryWhen(retrySpec)
                .timeout(duration, Mono.error(() -> new java.util.concurrent.TimeoutException("Response took longer than timeout: " + duration)))
                .doOnError(e -> LOG.error(e.getMessage(), e));
    }
Execute retry policy.

@param response   The Mono object of the response
@param exchange   Current Server Exchange Object
@param duration   TIMEOUT
@param retryTimes Number of retries
@return Response Mono object after retry processing
shenyu-plugin/shenyu-plugin-httpclient/src/main/java/org/apache/shenyu/plugin/httpclient/FixedRetryStrategy.java