Multiple text decoders

I seem to be getting `Text MessageHandler already registered` when trying to register multiple JSON decoders for multiple types of POJOs. Shouldn't it be possible to register multiple types of decoders for the same type, considering there is `Boolean willDecode(String)` method in `Decoder.Text` interface?
For example:
```java
void onOpen(Session session)
{
session.addMessageHandler(GatewayHello.class, this::onHello);
session.addMessageHandler(GatewayAck.class, this::onGatewayAck);
session.addMessageHandler(GatewayInvalid.class, this::onGatewayInvalid);
}

void onHello(GatewayHello request)
{

}
void onGatewayAck(GatewayAck request)
{

}
void onGatewayInvalid(GatewayInvalid request)
{

}
```
And in `@ClientEndpoint` annotation
```java
@ClientEndpoint(
decoders = {HelloDecoder.class, AckDecoder.class, InvalidDecoder.class}
)
```