当我安装ionic-push插件并在真实设备上运行该应用程序时，我正在使用两个Google插件作为服务，一个是位置服务，另一个是phonegap-push插件，出现以下错误：-
* What went wrong:
A problem occurred evaluating root project 'android'.
> Failed to apply plugin [class 'com.google.gms.googleservices.GoogleServicesPlugin']
> For input string: "+"
* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.
Picked up JAVA_TOOL_OPTIONS: -Djava.vendor="Sun Microsystems Inc."
(node:4872) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): Error: cmd: Command failed with exit code 1 Error output:
FAILURE: Build failed with an exception.
我通过Internet尝试了一些解决方案，但并没有帮助我。下面我粘贴了我的项目属性文件：-
# Project target.
target=android-26
android.library.reference.1=CordovaLib
cordova.gradle.include.1=phonegap-plugin-barcodescanner/testApplication-barcodescanner.gradle
cordova.system.library.1=com.android.support:support-v4:26.0+
cordova.system.library.2=com.google.android.gms:play-services-analytics:+
cordova.system.library.3=com.android.support:support-v4:24.1.1+
cordova.gradle.include.2=cordova-plugin-mauron85-background-geolocation/ebsMobileApps-logtofile.gradle
cordova.system.library.6=com.google.android.gms:play-services-location:11.6.0
cordova.system.library.5=com.android.support:support-v4:23+
cordova.gradle.include.3=cordova-android-play-services-gradle-release/ebsMobileApps-cordova-android-play-services-gradle-release.gradle
cordova.system.library.6=com.android.support:support-v13:26.+
cordova.system.library.7=me.leolin:ShortcutBadger:1.1.17@aar
cordova.system.library.8=com.google.firebase:firebase-messaging:11.6.2
cordova.gradle.include.4=phonegap-plugin-push/ebsMobileApps-push.gradle
cordova.system.library.9=com.google.firebase:firebase-messaging:11.+
请帮助解决问题。谢谢