生成Android应用APK时出错

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错误信息如下：
Warning:com.google.gson.jpush.internal.ab: can't find referenced class com.google.gson.jpush.internal.w$com.google.gson.jpush.internal.ac
Warning:com.google.gson.jpush.internal.w: can't find referenced class com.google.gson.jpush.internal.w$com.google.gson.jpush.internal.y
Warning:com.google.gson.jpush.internal.w: can't find referenced class com.google.gson.jpush.internal.w$com.google.gson.jpush.internal.aa
Warning:com.google.gson.jpush.internal.z: can't find referenced class com.google.gson.jpush.internal.w$com.google.gson.jpush.internal.ac
Warning:there were 4 unresolved references to classes or interfaces.
Warning:Exception while processing task java.io.IOException: Please correct the above warnings first.
Error:Execution failed for task ':app:transformClassesAndResourcesWithProguardForRelease'.

java.io.IOException: Please correct the above warnings first.