Matrix
constructor(baseUrl: Url? = null, authProvider: MatrixAuthProvider = MatrixAuthProvider.classicInMemory(), eventContentSerializerMappings: EventContentSerializerMappings = DefaultEventContentSerializerMappings, json: Json = createMatrixEventJson(eventContentSerializerMappings), httpClientEngine: HttpClientEngine? = null, httpClientConfig: HttpClientConfig<*>.() -> Unit? = null)