add validity on device X.509 certificate over MQTT transport connection

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

@@ -68,6 +68,7 @@ import java.util.List;
 import java.util.UUID;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
+import java.util.Date;
 
 import static io.netty.handler.codec.mqtt.MqttConnectReturnCode.CONNECTION_ACCEPTED;
 import static io.netty.handler.codec.mqtt.MqttConnectReturnCode.CONNECTION_REFUSED_NOT_AUTHORIZED;
@@ -386,6 +387,7 @@ public class MqttTransportHandler extends ChannelInboundHandlerAdapter implement
 
     private void processX509CertConnect(ChannelHandlerContext ctx, X509Certificate cert) {
         try {
+            cert.checkValidity(new Date());
             String strCert = SslUtil.getX509CertificateString(cert);
             String sha3Hash = EncryptionUtil.getSha3Hash(strCert);
             transportService.process(DeviceTransportType.MQTT, ValidateDeviceX509CertRequestMsg.newBuilder().setHash(sha3Hash).build(),