Add clean session flag to MQTT Node configuration.

rule-engine/rule-engine-components/src/main/java/org/thingsboard/rule/engine/mqtt/TbMqttNode.java

@@ -111,6 +111,7 @@ public class TbMqttNode implements TbNode {
         if (!StringUtils.isEmpty(this.config.getClientId())) {
             config.setClientId(this.config.getClientId());
         }
+        config.setCleanSession(this.config.isCleanSession());
         this.config.getCredentials().configure(config);
         MqttClient client = MqttClient.create(config);
         client.setEventLoop(this.eventLoopGroup);

rule-engine/rule-engine-components/src/main/java/org/thingsboard/rule/engine/mqtt/TbMqttNodeConfiguration.java

@@ -30,6 +30,7 @@ public class TbMqttNodeConfiguration implements NodeConfiguration<TbMqttNodeConf
     private int connectTimeoutSec;
     private String clientId;
 
+    private boolean cleanSession;
     private boolean ssl;
     private MqttClientCredentials credentials;
 
@@ -40,6 +41,7 @@ public class TbMqttNodeConfiguration implements NodeConfiguration<TbMqttNodeConf
         configuration.setHost("localhost");
         configuration.setPort(1883);
         configuration.setConnectTimeoutSec(10);
+        configuration.setCleanSession(true);
         configuration.setSsl(false);
         configuration.setCredentials(new AnonymousCredentials());
         return configuration;