#vulnerable code 
                                public HttpResponse execute(HttpHost target, HttpRequest request, HttpContext context)
            throws IOException {

        // default response context
        setResponseStatus(context, CacheResponseStatus.CACHE_MISS);

        String via = generateViaHeader(request);

        if (clientRequestsOurOptions(request)) {
            setResponseStatus(context, CacheResponseStatus.CACHE_MODULE_RESPONSE);
            return new OptionsHttp11Response();
        }

        HttpResponse fatalErrorResponse = getFatallyNoncompliantResponse(
                request, context);
        if (fatalErrorResponse != null) return fatalErrorResponse;

        request = requestCompliance.makeRequestCompliant(request);
        request.addHeader("Via",via);

        flushEntriesInvalidatedByRequest(target, request);

        if (!cacheableRequestPolicy.isServableFromCache(request)) {
            return callBackend(target, request, context);
        }

        HttpCacheEntry entry = satisfyFromCache(target, request);
        if (entry == null) {
            return handleCacheMiss(target, request, context);
        }

        return handleCacheHit(target, request, context, entry);
    } 
                            #location 7 
                            #vulnerability type INTERFACE_NOT_THREAD_SAFE
#fixed code
                                public HttpResponse execute(HttpHost target, HttpRequest request, HttpContext context)
            throws IOException {

        // default response context
        setResponseStatus(context, CacheResponseStatus.CACHE_MISS);

        String via = generateViaHeader(request);
        
        if (clientRequestsOurOptions(request)) {
            setResponseStatus(context, CacheResponseStatus.CACHE_MODULE_RESPONSE);
            return new OptionsHttp11Response();
        }

        HttpResponse fatalErrorResponse = getFatallyNoncompliantResponse(
                request, context);
        if (fatalErrorResponse != null) return fatalErrorResponse;

        request = requestCompliance.makeRequestCompliant(request);
        request.addHeader("Via",via);

        flushEntriesInvalidatedByRequest(target, request);

        if (!cacheableRequestPolicy.isServableFromCache(request)) {
            return callBackend(target, request, context);
        }

        HttpCacheEntry entry = satisfyFromCache(target, request);
        if (entry == null) {
            return handleCacheMiss(target, request, context);
        }

        return handleCacheHit(target, request, context, entry);
    }