@jroper This test fails because when writing 
```
Action {
  Ok
}
```

Play generates:
```
200 Ok

```

with no body nor `Content-Length: 0`. Which is against the rfc of http which specifies all replies should have a body or `Content-Length: 0`. 
I was thinking about making Enumerator contravariant (I think it's contravariant, I always mix up when talking about variance) which would permit Enumerator.empty to be a val (Enumerator[Nothing]) and matching against this val in the NettyResultStreamer to see if the body is intentionally empty and then add the `Content-Length: 0` header.