CEF module: Creates an empty pipeline?

When running with `--modules cef`, I see this in the stats API:

```
% curl -s localhost:9600/_node/stats | jq '.pipelines | to_entries[] | .key'
"main"
"module-cef"
```

Two pipelines. The `module-cef` pipeline is empty?

```
% curl -s localhost:9600/_node/stats | jq '.pipelines["module-cef"]'
{
"events": null,
"plugins": {
"inputs": [],
"filters": [],
"outputs": []
},
"reloads": {
"last_error": null,
"successes": 0,
"last_success_timestamp": null,
"last_failure_timestamp": null,
"failures": 0
},
"queue": null
}
```

The `main` pipeline appears to be the one configured by the CEF module.

This seems unexpected. What is this second `module-cef` pipeline?