MQTT: fix unsubscribe error without previous subscribe (#12575)

improved formatting and moved check to recordActivityInternal.

Added warn log and check on provision

Updated license format

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

@@ -963,7 +963,7 @@ public class MqttTransportHandler extends ChannelInboundHandlerAdapter implement
                 unSubResults.add((short) MqttReasonCodes.UnsubAck.NO_SUBSCRIPTION_EXISTED.byteValue());
             }
         }
-        if (!activityReported) {
+        if (!activityReported && !deviceSessionCtx.isProvisionOnly()) {
             transportService.recordActivity(deviceSessionCtx.getSessionInfo());
         }
         ctx.writeAndFlush(createUnSubAckMessage(mqttMsg.variableHeader().messageId(), unSubResults));

common/transport/transport-api/src/main/java/org/thingsboard/server/common/transport/service/DefaultTransportService.java

@@ -736,7 +736,11 @@ public class DefaultTransportService extends TransportActivityManager implements
     }
 
     private void recordActivityInternal(TransportProtos.SessionInfoProto sessionInfo) {
-        onActivity(toSessionId(sessionInfo), sessionInfo, getCurrentTimeMillis());
+        if (sessionInfo != null) {
+            onActivity(toSessionId(sessionInfo), sessionInfo, getCurrentTimeMillis());
+        } else {
+            log.warn("Session info is missing, unable to record activity");
+        }
     }
 
     @Override