boolean etagValidatorMatches(final HttpRequest request, final HttpCacheEntry entry) {
        final ETag etag = entry.getETag();
        if (etag == null) {
            return false;
        }
        final Iterator<String> it = MessageSupport.iterateTokens(request, HttpHeaders.IF_NONE_MATCH);
        while (it.hasNext()) {
            final String token = it.next();
            if ("*".equals(token) || ETag.weakCompare(etag, ETag.parse(token))) {
                return true;
            }
        }
        return false;
    }
Check entry against If-None-Match
@param request The current httpRequest being made
@param entry the cache entry
@return boolean does the etag validator match
httpclient5-cache/src/main/java/org/apache/hc/client5/http/impl/cache/CachedResponseSuitabilityChecker.java