Channel (SmallRye Reactive Messaging 3.13.0 API)

```
@Qualifier
@Retention(RUNTIME)
@Target({METHOD,CONSTRUCTOR,FIELD,PARAMETER})
@Experimental("smallrye-only, added to the specification")
public @interface Channel
```
This qualifier indicates which channel should be injected / populated.
This qualifier can be used to inject a Channel containing the items and signals propagated by the specified channel. For example, it can be used to @Inject a Publisher representing a channel managed by the Reactive Messaging implementation.
Can be injected:
- Publisher<X> with X the payload type
- Publisher<Message<X>> with X the payload type
- PublisherBuilder<Message<X>> with X the payload type
- PublisherBuilder<X> with X the payload type
When this qualifier is used on an Emitter, it indicates which channel received the emitted values / signals:
```
 
 @Inject @Channel("my-channel") Emitter<String> emitter;

 // ...
 emitter.send("a");
 
 
```
A subscriber for the above channel must be found by the time a message is emitted to the channel. Otherwise, IllegalStateException must be thrown.

- Required Element Summary
  
  Required Elements
  Modifier and Type Required Element Description
  
  String value
  The name of the channel (indicated in the @Outgoing annotation.

- Element Detail
  - value
```
String value
```
    The name of the channel (indicated in the @Outgoing annotation.
    
    Returns:
    
    the channel name, mandatory, non-null and non-blank. It must matches one of the available channels.