[Flutter] Namespace not specified. Specify a namespace in the module's build file:

I already did AGP Upgrade Assistant, but still having this error, it's related to .pub-cache.

FAILURE: Build failed with an exception.

• What went wrong: A problem occurred configuring project ':app_group_directory'.

Could not create an instance of type com.android.build.api.variant.impl.LibraryVariantBuilderImpl. Namespace not specified. Specify a namespace in the module's build file: /Users/armagangok/.pub-cache/hosted/pub.dev/app_group_directory-2.0.0/android/build.gradle. See https://d.android.com/r/tools/upgrade-assistant/set-namespace for information about setting the namespace.
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If you've specified the package attribute in the source AndroidManifest.xml, you can use the AGP Upgrade Assistant to migrate to the namespace value in the build file. Refer to https://d.android.com/r/tools/upgrade-assistant/agp-upgrade-assistant for general information about using the AGP Upgrade Assistant.

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