boolean clientRequestsOurOptions(final HttpRequest request) {
        if (!Method.OPTIONS.isSame(request.getMethod())) {
            return false;
        }

        if (!"*".equals(request.getRequestUri())) {
            return false;
        }

        final Header h = request.getFirstHeader(HttpHeaders.MAX_FORWARDS);
        return "0".equals(h != null ? h.getValue() : null);
    }
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