Improvements

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

@@ -175,7 +175,9 @@ public class MqttTransportHandler extends ChannelInboundHandlerAdapter implement
                 ctx.writeAndFlush(new MqttMessage(new MqttFixedHeader(PINGRESP, false, AT_MOST_ONCE, false, 0)));
                 break;
             case DISCONNECT:
-                ctx.close();
+                if (checkConnected(ctx, msg)) {
+                    processDisconnect(ctx);
+                }
                 break;
         }
     }

common/transport/mqtt/src/main/java/org/thingsboard/server/transport/mqtt/session/DeviceSessionCtx.java

@@ -49,7 +49,7 @@ public class DeviceSessionCtx extends MqttDeviceAwareSessionContext {
 
     @Getter
     @Setter
-    private boolean provisionOnly;
+    private boolean provisionOnly = false;
 
     private volatile MqttTopicFilter telemetryTopicFilter = MqttTopicFilterFactory.getDefaultTelemetryFilter();
     private volatile MqttTopicFilter attributesTopicFilter = MqttTopicFilterFactory.getDefaultAttributesFilter();