// 504 code indicates that the Cache is stale
        val onlyIfCached =
          CacheControl.Builder()
            .onlyIfCached()
            .build()

        var cacheUrl = request.url

        val cacheRequest =
          request.newBuilder()
            .cacheControl(onlyIfCached)
            .cacheUrlOverride(cacheUrl)
            .build()

	}

	if !objInfo.Expires.IsZero() {
		w.Header().Set(xhttp.Expires, objInfo.Expires.UTC().Format(http.TimeFormat))
	}

	if objInfo.CacheControl != "" {
		w.Header().Set(xhttp.CacheControl, objInfo.CacheControl)
	}
}

// Validates the preconditions. Returns true if GET/HEAD operation should not proceed.
// Preconditions supported are:
//
//	If-Modified-Since

	Connection         = "Connection"
	AcceptRanges       = "Accept-Ranges"
	AmzBucketRegion    = "X-Amz-Bucket-Region"
	ServerInfo         = "Server"
	RetryAfter         = "Retry-After"
	Location           = "Location"
	CacheControl       = "Cache-Control"
	ContentDisposition = "Content-Disposition"
	Authorization      = "Authorization"
	Action             = "Action"
	Range              = "Range"
)

// Non standard S3 HTTP response constants

		Legacy:           fi.XLV1,
		ContentType:      fi.Metadata["content-type"],
		ContentEncoding:  fi.Metadata["content-encoding"],
		NumVersions:      fi.NumVersions,
		SuccessorModTime: fi.SuccessorModTime,
		CacheControl:     fi.Metadata["cache-control"],
	}

	if exp, ok := fi.Metadata["expires"]; ok {
		if t, err := amztime.ParseHeader(exp); err == nil {
			objInfo.Expires = t.UTC()
		}
	}

		putOpts.ContentLanguage = lang
	}
	if disp, ok := lkMap.Lookup(xhttp.ContentDisposition); ok {
		putOpts.ContentDisposition = disp
	}
	if cc, ok := lkMap.Lookup(xhttp.CacheControl); ok {
		putOpts.CacheControl = cc
	}
	if mode, ok := lkMap.Lookup(xhttp.AmzObjectLockMode); ok {
		rmode := minio.RetentionMode(mode)
		putOpts.Mode = rmode
	}

var supportedHeadGetReqParams = map[string]string{
	"response-expires":             xhttp.Expires,
	"response-content-type":        xhttp.ContentType,
	"response-cache-control":       xhttp.CacheControl,
	"response-content-encoding":    xhttp.ContentEncoding,
	"response-content-language":    xhttp.ContentLanguage,
	"response-content-disposition": xhttp.ContentDisposition,
}

const (

@ElementTypesAreNonnullByDefault
public final class HttpHeaders {
  private HttpHeaders() {}

  // HTTP Request and Response header fields

  /** The HTTP {@code Cache-Control} header field name. */
  public static final String CACHE_CONTROL = "Cache-Control";
  /** The HTTP {@code Content-Length} header field name. */
  public static final String CONTENT_LENGTH = "Content-Length";
  /** The HTTP {@code Content-Type} header field name. */