SimpleHttpResponse generateGatewayTimeout() {
        return SimpleHttpResponse.create(HttpStatus.SC_GATEWAY_TIMEOUT, "Gateway Timeout");
    }
Reports the number of times that the cache was able to satisfy
a response by revalidating an existing but stale cache entry.
@return the number of cache revalidations
httpclient5-cache/src/main/java/org/apache/hc/client5/http/impl/cache/CachingExecBase.java