Using a nested polymophic relationship is not allowed in Azure services. Most JSON serializers and deserializers do not support this feature.

## Impact

- **Area:** SDK, API

Multiple discriminators are not supported by SDKs, nor by Swagger without extensions.

#### ❌ Incorrect

```tsp
@discriminator("fishtype")
model Fish {
  fishtype: string;
}

@discriminator("sharktype")
model Shark extends Fish {
  fishtype: "shark";
  sharktype: string;
}

model WhiteShark extends Shark {
  sharktype: "white";
}
```

#### ✅ Correct

```tsp
@discriminator("fishtype")
model Fish {
  fishtype: string;
}

model Shark extends Fish {
  fishtype: "shark";
}

model WhiteShark extends Fish {
  fishtype: "white-shark";
}
```

## Suppression

Suppress only with SDK approval. Use a single discriminator and refactor additional discriminators onto child or sibling properties.
