我遇到问题。\n我无法使用 OneSignal。我不知道为什么。我用谷歌搜索了该错误，但没有任何帮助。
\n目前我使用 Android Studio 版本：4.2\n最新的 OneSignal 版本：4.3.4\n还有最新的 Firebase 版本。我创建了一个新的 Firebase 项目和 OneSignal 项目。
\n这是错误：
\n2021-05-25 13:06:37.370 3225-4181/de.kggaming.application E/OneSignal: Unknown error getting FCM Token\n java.lang.NoClassDefFoundError: Failed resolution of: Lcom/google/firebase/iid/FirebaseInstanceId;\n at com.onesignal.PushRegistratorFCM.getToken(PushRegistratorFCM.java:60)\n at com.onesignal.PushRegistratorAbstractGoogle.attemptRegistration(PushRegistratorAbstractGoogle.java:97)\n at com.onesignal.PushRegistratorAbstractGoogle.access$100(PushRegistratorAbstractGoogle.java:37)\n at com.onesignal.PushRegistratorAbstractGoogle$1.run(PushRegistratorAbstractGoogle.java:84)\n at java.lang.Thread.run(Thread.java:923)\n Caused by: java.lang.ClassNotFoundException: Didn't find class "com.google.firebase.iid.FirebaseInstanceId" on path: DexPathList[[dex file "/data/data/de.kggaming.application/code_cache/.overlay/base.apk/classes3.dex", zip file "/data/app/~~37wP-zifceloViDoIaZiLQ==/de.kggaming.application-MT0rnPML9HHvlPgijekxXw==/base.apk"],nativeLibraryDirectories=[/data/app/~~37wP-zifceloViDoIaZiLQ==/de.kggaming.application-MT0rnPML9HHvlPgijekxXw==/lib/arm64, /system/lib64]]\n at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:207)\n at java.lang.ClassLoader.loadClass(ClassLoader.java:379)\n at java.lang.ClassLoader.loadClass(ClassLoader.java:312)\n at com.onesignal.PushRegistratorFCM.getToken(PushRegistratorFCM.java:60)\xc2\xa0\n at com.onesignal.PushRegistratorAbstractGoogle.attemptRegistration(PushRegistratorAbstractGoogle.java:97)\xc2\xa0\n at com.onesignal.PushRegistratorAbstractGoogle.access$100(PushRegistratorAbstractGoogle.java:37)\xc2\xa0\n at com.onesignal.PushRegistratorAbstractGoogle$1.run(PushRegistratorAbstractGoogle.java:84)\xc2\xa0\n at java.lang.Thread.run(Thread.java:923)\xc2\xa0\n这是我的 build.gradle （项目）：
\n// …