feat(mqtt): add getVersion method to MqttConnectMessage

- Added getVersion() method to MqttConnectMessage class - Removed getVersion() method from MqttMessage base class - Improved MQTT version access consistency in message handling

Author: smthing

smart-mqtt-common/src/main/java/tech/smartboot/mqtt/common/message/MqttConnectMessage.java

@@ -121,4 +121,8 @@ public void decodePlayLoad(ByteBuffer buffer) {
  public MqttConnectPayload getPayload() {
  return mqttConnectPayload;
  }
+
+ public MqttVersion getVersion() {
+ return version;
+ }
 }

smart-mqtt-common/src/main/java/tech/smartboot/mqtt/common/message/MqttMessage.java

@@ -111,10 +111,6 @@ public void setRemainingLength(int remainingLength) {
  this.remainingLength = remainingLength;
  }
 
- public final MqttVersion getVersion() {
- return version;
- }
-
  public final void setVersion(MqttVersion version) {
  this.version = version;
  }