fix: preserve multipart defaults and rollback compatibility

Signed-off-by: Feng Ruohang <rh@vonng.com>

cmd/handler-api.go

@@ -50,7 +50,7 @@ type apiConfig struct {
 	transitionWorkers      int
 
 	staleUploadsExpiry          time.Duration
-	multipartListingLegacy      bool
+	multipartListingStrict      bool
 	staleUploadsCleanupInterval time.Duration
 	deleteCleanupInterval       time.Duration
 	enableODirect               bool
@@ -182,7 +182,7 @@ func (t *apiConfig) init(cfg api.Config, setDriveCounts []int, legacy bool) {
 	t.transitionWorkers = cfg.TransitionWorkers
 
 	t.staleUploadsExpiry = cfg.StaleUploadsExpiry
-	t.multipartListingLegacy = cfg.MultipartListing == "legacy"
+	t.multipartListingStrict = cfg.MultipartListing == "strict"
 	t.deleteCleanupInterval = cfg.DeleteCleanupInterval
 	t.enableODirect = cfg.EnableODirect
 	t.gzipObjects = cfg.GzipObjects
@@ -211,7 +211,7 @@ func (t *apiConfig) odirectEnabled() bool {
 func (t *apiConfig) getMultipartListingLegacy() bool {
 	t.mu.RLock()
 	defer t.mu.RUnlock()
-	return t.multipartListingLegacy
+	return !t.multipartListingStrict
 }
 
 func (t *apiConfig) shouldGzipObjects() bool {