Refactored due to comments

common/transport/mqtt/src/main/java/org/thingsboard/server/transport/mqtt/MqttTransportHandler.java

@@ -314,26 +314,8 @@ public class MqttTransportHandler extends ChannelInboundHandlerAdapter implement
                 }
                 break;
             case SUBSCRIBE:
-                MqttSubscribeMessage mqttSubscribeMsg = (MqttSubscribeMessage) msg;
-                log.trace("[{}] Processing subscription [{}]!", sessionId, mqttSubscribeMsg.variableHeader().messageId());
-                List<Integer> grantedQoSList = new ArrayList<>();
-                for (MqttTopicSubscription subscription : mqttSubscribeMsg.payload().topicSubscriptions()) {
-                    String topic = subscription.topicFilter();
-                    MqttQoS reqQoS = subscription.qualityOfService();
-                    try {
-                        if (MqttTopics.DEVICE_PROVISION_RESPONSE_TOPIC.equals(topic)) {
-                            registerSubQoS(topic, grantedQoSList, reqQoS);
-                        } else {
-                            log.warn("[{}] Failed to subscribe to [{}][{}]", sessionId, topic, reqQoS);
-                            grantedQoSList.add(ReturnCodeResolver.getSubscriptionReturnCode(deviceSessionCtx.getMqttVersion(), MqttReasonCodes.SubAck.TOPIC_FILTER_INVALID));
-                            break;
-                        }
-                    } catch (Exception e) {
-                        log.warn("[{}] Failed to subscribe to [{}][{}]", sessionId, topic, reqQoS, e);
-                        grantedQoSList.add(ReturnCodeResolver.getSubscriptionReturnCode(deviceSessionCtx.getMqttVersion(), MqttReasonCodes.SubAck.IMPLEMENTATION_SPECIFIC_ERROR));
-                    }
-                }
-                ctx.writeAndFlush(createSubAckMessage(mqttSubscribeMsg.variableHeader().messageId(), grantedQoSList));
+                MqttSubscribeMessage subscribeMessage = (MqttSubscribeMessage) msg;
+                processSubscribe(ctx, subscribeMessage);
                 break;
             case PINGREQ:
                 ctx.writeAndFlush(new MqttMessage(new MqttFixedHeader(PINGRESP, false, AT_MOST_ONCE, false, 0)));
@@ -772,7 +754,7 @@ public class MqttTransportHandler extends ChannelInboundHandlerAdapter implement
     }
 
     private void processSubscribe(ChannelHandlerContext ctx, MqttSubscribeMessage mqttMsg) {
-        if (!checkConnected(ctx, mqttMsg)) {
+        if (!checkConnected(ctx, mqttMsg) && !deviceSessionCtx.isProvisionOnly()) {
             ctx.writeAndFlush(createSubAckMessage(mqttMsg.variableHeader().messageId(), Collections.singletonList(MqttReasonCodes.SubAck.NOT_AUTHORIZED.byteValue() & 0xFF)));
             return;
         }
@@ -782,6 +764,16 @@ public class MqttTransportHandler extends ChannelInboundHandlerAdapter implement
         for (MqttTopicSubscription subscription : mqttMsg.payload().topicSubscriptions()) {
             String topic = subscription.topicName();
             MqttQoS reqQoS = subscription.qualityOfService();
+            if (deviceSessionCtx.isProvisionOnly()) {
+                if (MqttTopics.DEVICE_PROVISION_RESPONSE_TOPIC.equals(topic)) {
+                    registerSubQoS(topic, grantedQoSList, reqQoS);
+                } else {
+                    log.debug("[{}] Failed to subscribe to [{}][{}]", sessionId, topic, reqQoS);
+                    grantedQoSList.add(ReturnCodeResolver.getSubscriptionReturnCode(deviceSessionCtx.getMqttVersion(), MqttReasonCodes.SubAck.TOPIC_FILTER_INVALID));
+                }
+                activityReported = true;
+                continue;
+            }
             if (deviceSessionCtx.isDeviceSubscriptionAttributesTopic(topic)) {
                 processAttributesSubscribe(grantedQoSList, topic, reqQoS, TopicType.V1);
                 activityReported = true;