[fix][doc] fix schema get value doc problem
@@ -278,7 +278,7 @@ Pulsar gets the schema definition from the predefined `struct` using an Avro lib
```java
Consumer<User> consumer = client.newConsumer(Schema.AVRO(User.class)).subscribe();
- User user = consumer.receive();
+ User user = consumer.receive().getValue();
```
</TabItem>
