[FIXED] Creating ephemeral consumers on server < 2.9.0 (#1325)

Signed-off-by: Piotr Piotrowski <[email protected]>

jsm.go

@@ -361,20 +361,29 @@ func (js *js) upsertConsumer(stream, consumerName string, cfg *ConsumerConfig, o
 
 	var ccSubj string
 	if consumerName == _EMPTY_ {
-		// if consumer name is empty, use the legacy ephemeral endpoint
+		// if consumer name is empty (neither Durable nor Name is set), use the legacy ephemeral endpoint
 		ccSubj = fmt.Sprintf(apiLegacyConsumerCreateT, stream)
 	} else if err := checkConsumerName(consumerName); err != nil {
 		return nil, err
-	} else if !js.nc.serverMinVersion(2, 9, 0) || (cfg.Durable != "" && js.opts.featureFlags.useDurableConsumerCreate) {
-		// if server version is lower than 2.9.0 or user set the useDurableConsumerCreate flag, use the legacy DURABLE.CREATE endpoint
-		ccSubj = fmt.Sprintf(apiDurableCreateT, stream, consumerName)
-	} else {
-		// if above server version 2.9.0, use the endpoints with consumer name
-		if cfg.FilterSubject == _EMPTY_ || cfg.FilterSubject == ">" {
+	} else if js.nc.serverMinVersion(2, 9, 0) {
+		if cfg.Durable != "" && js.opts.featureFlags.useDurableConsumerCreate {
+			// if user set the useDurableConsumerCreate flag, use the legacy DURABLE.CREATE endpoint
+			ccSubj = fmt.Sprintf(apiDurableCreateT, stream, consumerName)
+		} else if cfg.FilterSubject == _EMPTY_ || cfg.FilterSubject == ">" {
+			// if filter subject is empty or ">", use the endpoint without filter subject
 			ccSubj = fmt.Sprintf(apiConsumerCreateT, stream, consumerName)
 		} else {
+			// if filter subject is not empty, use the endpoint with filter subject
 			ccSubj = fmt.Sprintf(apiConsumerCreateWithFilterSubjectT, stream, consumerName, cfg.FilterSubject)
 		}
+	} else {
+		if cfg.Durable != "" {
+			// if Durable is set, use the DURABLE.CREATE endpoint
+			ccSubj = fmt.Sprintf(apiDurableCreateT, stream, consumerName)
+		} else {
+			// if Durable is not set, use the legacy ephemeral endpoint
+			ccSubj = fmt.Sprintf(apiLegacyConsumerCreateT, stream)
+		}
 	}
 
 	resp, err := js.apiRequestWithContext(o.ctx, js.apiSubj(ccSubj), req)