interface Credentials {  enum class Provider {    ANONYMOUS("anon-user"),
    API_KEY("api-key"),    // same value as API_KEY as per OS specifications
    APPLE("oauth2-apple"),
    CUSTOM_FUNCTION("custom-function"),
    EMAIL_PASSWORD("local-userpass"),
    FACEBOOK("oauth2-facebook"),
    GOOGLE("oauth2-google"),
    JWT("jwt"),
    UNKNOWN("");  }  companion object {
    fun anonymous(): Credentials
    fun apiKey(key: String): Credentials
    fun apple(idToken: String): Credentials
    fun customFunction(args: Document): Credentials
    fun emailPassword(email: String, password: String): Credentials
    fun facebook(accessToken: String): Credentials    fun google(token: String, type: GoogleAuthType): Credentials    fun jwt(jwtToken: String): Credentials
  }  
  val identityProvider: Provider  fun asJson(): String
}

class io.realm.mongodb.App {
  suspend fun login(credentials: Credentials): User 
}