Unity6; Automatic Android migration

[jkasten2]

Description

One Line Summary

Automatically apply required changes for Unity 6 build compatibility, this only effects Android.

Details

Follow up to PR #776

Motivation

If changes were not applied automatic it will lead extra work the app developer has to search for or may reach out to OneSignal support for help.

Scope

Only effects Android builds.

Testing

Unit testing

None

Manual testing

Tested with Unity 6000.0.42f1.7976.8784 on macOS.
Made changes to the file located at Assets/Plugins/Android/OneSignalConfig.androidlib/build.gradle and ensured it reverts it.

Affected code checklist

• Notifications
  • Display
  • Open
  • Push Processing
  • Confirm Deliveries
• Outcomes
• Sessions
• In-App Messaging
• REST API requests
• Public API changes

Checklist

Overview

• I have filled out all REQUIRED sections above
• PR does one thing
• Any Public API changes are explained in the PR details and conform to existing APIs

Testing

• I have included test coverage for these changes, or explained why they are not needed
• All automated tests pass, or I explained why that is not possible
• I have personally tested this on my device, or explained why that is not possible

Final pass

• Code is as readable as possible.
• I have reviewed this PR myself, ensuring it meets each checklist item
  • WIP (Work In Progress) is ok, but explain what is still in progress and what you would like feedback on. Start the PR title with "WIP" to indicate this.

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This change is 

[nan-li]

I am not familiar with our Unity SDK process, is my understanding below correct?

1. I don’t see where this new class is being called, so this class is automatically initialized due to InitializeOnLoad ?

2. The main logic effectively takes the contents that is in com.onesignal.unity.android/Editor/OneSignalConfig.androidlib/build.gradle and replaces the contents in the file OneSignalExample/Assets/Plugins/Android/OneSignalConfig.androidlib/build.gradle , for example, if they are different. This is because the file OneSignalExample/Assets/Plugins/Android/OneSignalConfig.androidlib/build.gradle is automatically generated and consumers wouldn’t manipulate this file themselves, but this file may not automatically update when com.onesignal.unity.android/Editor/OneSignalConfig.androidlib/build.gradle changes. Hence, why we need to do this migration step to save the client a hassle and questions?

[jkasten2]

1. Yes, the [InitializeOnLoad] means Unity will call the static constructor in a few scenarios; A. the SDK is added; B. The SDK is updated;
2. Correct