Firebase Dynamiclink每次以dynamic_link_first_open触发

Question

我使用Firebase Dynamiclink进行跟踪。但是，每次我单击链接时，即使再次单击相同的链接，事件也会触发为dynamic_link_first_open。

我的FirebaseCore是5.1.9，而FirebaseDynamicLinks是3.3.0。
这是我的代码。

@available(iOS 9.0, *)
func application(_ app: UIApplication, open url: URL, options: [UIApplicationOpenURLOptionsKey : Any]) -> Bool {
    return application(app, open: url,
                       sourceApplication: options[UIApplicationOpenURLOptionsKey.sourceApplication] as? String,
                       annotation: "")
}

func application(_ application: UIApplication, open url: URL, sourceApplication: String?, annotation: Any) -> Bool {
    if let dynamicLink = DynamicLinks.dynamicLinks().dynamicLink(fromCustomSchemeURL: url) {
        // Handle the link 
        return true
    }
    return false
}

func application(_ application: UIApplication, continue userActivity: NSUserActivity, restorationHandler: @escaping ([Any]?) -> Void) -> Bool {

    let _ = DynamicLinks.dynamicLinks().handleUniversalLink(incomingUrl, completion: {
        (dynamiclink, error) in
        if let _ = dynamiclink?.url {
            // Handle the link
        }
    })
}

dynamic_link事件如何在first_open和app_open之间分类？