When using the addNestjsRestParameter option it also modifies the signature of the client methods, resulting in the following output:

export interface SampleClient {
    log(request: Event, metadata: Metadata, ...rest: any): Observable<Unused>;
}
export interface SampleServiceController {
    log(request: Event, metadata: Metadata, ...rest: any): Promise<Unused> | Observable<Unused> | Unused;
}

The additional rest parameter should not apply to client calls. The way it stands, this signature requires Metadata to be set on all client calls, which is not required by gRPC.