Add null point check before send message with namespace

client/src/main/java/org/apache/rocketmq/client/producer/DefaultMQProducer.java

@@ -331,6 +331,7 @@ public class DefaultMQProducer extends ClientConfig implements MQProducer {
     @Override
     public SendResult send(
         Message msg) throws MQClientException, RemotingException, MQBrokerException, InterruptedException {
+        Validators.checkMessage(msg,this);
         msg.setTopic(withNamespace(msg.getTopic()));
         return this.defaultMQProducerImpl.send(msg);
     }