flutter插件引用aar导致Duplicate class android.support.v4.app.INotificationSideChannel

错误信息

Duplicate class android.support.v4.app.INotificationSideChannel$Stub found in modules classes.jar (androidx.core:core:1.0.1) and classes.jar (com.android.support:support-compat:28.0.0)
Duplicate class android.support.v4.app.INotificationSideChannel$Stub$Proxy found in modules classes.jar (androidx.core:core:1.0.1) and classes.jar (com.android.support:support-compat:28.0.0)
Duplicate class android.support.v4.graphics.drawable.IconCompatParcelizer found in modules classes.jar (androidx.core:core:1.0.1) and classes.jar (com.android.support:support-compat:28.0.0)
Duplicate class android.support.v4.os.IResultReceiver found in modules classes.jar (androidx.core:core:1.0.1) and classes.jar (com.android.support:support-compat:28.0.0)
Duplicate class android.support.v4.os.IResultReceiver$Stub found in modules classes.jar (androidx.core:core:1.0.1) and classes.jar (com.android.support:support-compat:28.0.0)
Duplicate class android.support.v4.os.IResultReceiver$Stub$Proxy found in modules classes.jar (androidx.core:core:1.0.1) and classes.jar (com.android.support:support-compat:28.0.0)
Duplicate class android.support.v4.os.ResultReceiver found in modules classes.jar (androidx.core:core:1.0.1) and classes.jar (com.android.support:support-compat:28.0.0)
Duplicate class android.support.v4.os.ResultReceiver$1 found in modules classes.jar (androidx.core:core:1.0.1) and classes.jar (com.android.support:support-compat:28.0.0)
Duplicate class android.support.v4.os.ResultReceiver$MyResultReceiver found in modules classes.jar (androidx.core:core:1.0.1) and classes.jar (com.android.support:support-compat:28.0.0)

原因

• aar中使用了androidx，example project也需要使用androidx

解决方法

• 执行refactor -> Migrate to AndroidX
• 检查example\android\gradle.properties, 确保已经加入下面两行（migrate应该会自动添加，但我还是手动添加了）

android.useAndroidX=true
android.enableJetifier=true