Custom Span Names for Interceptors based solution

Hi, 

I have the following issue: I'm using Quarkus with interceptors:

```
...
...
mp.messaging.outgoing.datagen-tickets-out.interceptor.classes=io.opentracing.contrib.kafka.TracingProducerInterceptor
```

I'm reading the documentation and code but I don't find how to modify the span names. Is it possible with interceptors?

Thank you
