Use
constructor(api: String = "/api/completion", id: String = generateId("completion"), initialCompletion: String = "", initialInput: String = "", headers: Map<String, String> = emptyMap(), body: Map<String, JsonElement> = emptyMap(), streamProtocol: CompletionStreamProtocol = CompletionStreamProtocol.Data, transport: CompletionTransport = DirectCompletionTransport { emptyFlow() }, onFinish: suspend (prompt: String, completion: String) -> Unit = { _, _ -> }, onError: suspend (Throwable) -> Unit = {})