#vulnerable code 
                                HttpCacheEntry doGetUpdatedParentEntry(
            final String requestId,
            final HttpCacheEntry existing,
            final HttpCacheEntry entry,
            final String variantURI) throws IOException {
        if (existing != null) {
            return cacheEntryFactory.copyVariant(requestId, existing, variantURI);
        } else {
            return cacheEntryFactory.copyVariant(requestId, entry, variantURI);
        }
    } 
                            #location 7 
                            #vulnerability type INTERFACE_NOT_THREAD_SAFE
#fixed code
                                CachingHttpClient(HttpClient backend, CacheValidityPolicy validityPolicy, ResponseCachingPolicy responseCachingPolicy,
                             CacheEntryFactory cacheEntryFactory, URIExtractor uriExtractor,
                             HttpCache responseCache, CachedHttpResponseGenerator responseGenerator,
                             CacheInvalidator cacheInvalidator, CacheableRequestPolicy cacheableRequestPolicy,
                             CachedResponseSuitabilityChecker suitabilityChecker,
                             ConditionalRequestBuilder conditionalRequestBuilder, CacheEntryUpdater entryUpdater,
                             ResponseProtocolCompliance responseCompliance,
                             RequestProtocolCompliance requestCompliance) {
        CacheConfig config = new CacheConfig();
        this.maxObjectSizeBytes = config.getMaxObjectSizeBytes();
        this.sharedCache = config.isSharedCache();
        this.backend = backend;
        this.cacheEntryFactory = cacheEntryFactory;
        this.validityPolicy = validityPolicy;
        this.responseCachingPolicy = responseCachingPolicy;
        this.uriExtractor = uriExtractor;
        this.responseCache = responseCache;
        this.responseGenerator = responseGenerator;
        this.cacheInvalidator = cacheInvalidator;
        this.cacheableRequestPolicy = cacheableRequestPolicy;
        this.suitabilityChecker = suitabilityChecker;
        this.conditionalRequestBuilder = conditionalRequestBuilder;
        this.cacheEntryUpdater = entryUpdater;
        this.responseCompliance = responseCompliance;
        this.requestCompliance = requestCompliance;
    }