// for validation during GET/HEAD object requests.
type CondCheck struct {
	ObjectInfo
	IfMatch           string     `json:"ifMatch,omitempty" msg:",omitempty"`
	IfNoneMatch       string     `json:"ifNoneMatch,omitempty" msg:",omitempty"`
	IfModifiedSince   *time.Time `json:"ifModSince,omitempty" msg:",omitempty"`
	IfUnModifiedSince *time.Time `json:"ifUnmodSince,omitempty" msg:",omitempty"`

				return
			}
		case "IfMatch":
			z.IfMatch, err = dc.ReadString()
			if err != nil {
				err = msgp.WrapError(err, "IfMatch")
				return
			}
		case "IfNoneMatch":
			z.IfNoneMatch, err = dc.ReadString()
			if err != nil {
				err = msgp.WrapError(err, "IfNoneMatch")
				return
			}
		case "IfModifiedSince":
			if dc.IsNil() {
				err = dc.ReadNil()
				if err != nil {
					err = msgp.WrapError(err, "IfModifiedSince")

		}
	}

	// If-None-Match : Return the object only if its entity tag (ETag) is different from the
	// one specified otherwise, return a 304 (not modified).
	ifNoneMatchETagHeader := r.Header.Get(xhttp.IfNoneMatch)
	if ifNoneMatchETagHeader != "" {
		if isETagEqual(objInfo.ETag, ifNoneMatchETagHeader) {
			// If the object ETag matches with the specified ETag.
			writeHeaders()

	XCacheLookup = "X-Cache-Lookup"
)

// Standard S3 HTTP request constants
const (
	IfModifiedSince   = "If-Modified-Since"
	IfUnmodifiedSince = "If-Unmodified-Since"
	IfMatch           = "If-Match"
	IfNoneMatch       = "If-None-Match"

	// Request tags used in GetObjectAttributes
	Checksum     = "Checksum"
	StorageClass = "StorageClass"
	ObjectSize   = "ObjectSize"
	ObjectParts  = "ObjectParts"

	// S3 storage class

    // Seed the cache.
    val url = server.url("/")
    assertThat(get(url).body.string()).isEqualTo("A")
    val ifNoneMatch = AtomicReference<String?>()
    client =
      client.newBuilder()
        .addNetworkInterceptor(
          Interceptor { chain: Interceptor.Chain ->
            ifNoneMatch.compareAndSet(null, chain.request().header("If-None-Match"))
            chain.proceed(chain.request())
          },

	if err != nil {
		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
		return
	}

	if opts.PreserveETag != "" ||
		r.Header.Get(xhttp.IfMatch) != "" ||
		r.Header.Get(xhttp.IfNoneMatch) != "" {
		opts.CheckPrecondFn = func(oi ObjectInfo) bool {
			if _, err := DecryptObjectInfo(&oi, r); err != nil {
				writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
				return true
			}

		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
		return
	}
	opts.IndexCB = idxCb

	if opts.PreserveETag != "" ||
		r.Header.Get(xhttp.IfMatch) != "" ||
		r.Header.Get(xhttp.IfNoneMatch) != "" {
		opts.CheckPrecondFn = func(oi ObjectInfo) bool {
			if _, err := DecryptObjectInfo(&oi, r); err != nil {
				writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
				return true
			}