Overview

The External Dependency Manager for Unity (EDM4U) is a package manager for Android-native .aar library dependencies. The EDM4U automatically downloads all necessary packages and resolves any version conflicts, and MetaplaySDK uses EDM4U to manage Android dependencies. The EDM4U is not bundled into the MetaplaySDK and may require manual installation for successful Android builds. This document describes the necessary installation steps.

Installation Guide

Many Google packages, such as for Firebase, automatically bundle EDM4U, making it almost always present in any Android-targeting project. To check if EDM4U is already installed, switch the Unity project platform to Android and look into the application menu bar. If Menu > Assets > External Dependency Manager exists, the EDM4U is successfully installed.

Installing the External Dependency Manager Manually

If EDM4U is not already installed, you can install it manually. EDM4U is delivered as a Unity Package Manager package, but it's not available in Unity's repository. To install the package manually:

1. Download the .tgz file from Google APIs for Unity and place it in the Packages/ directory.
2. Follow the instructions in Google's Documentation.

Note that the Unity Package Manager UI may automatically use absolute paths in Packages/manifest.json. To avoid issues with version control and different paths for different users, convert the path to the relative form, such as file:com.google.external-dependency-manager-1.2.172.tgz if the .tgz file is placed in the Packages/ directory.

Alternatively, you may follow the official instructions for installing the package using OpenUPM.

Upon installation, the EDM4U will perform package resolution and will download the necessary Android libraries to the Assets/Plugins/Android directory. It is convenient to commit these libraries into version control.

💡 Manual Dependency Management

If the automatic dependency resolution of EDM4U is not suitable and you need to manage Android dependencies manually, you can do so by defining the METAPLAY_DISABLE_GOOGLE_EDM4U_CHECK symbol. This disables the safety check in MetaplaySDK which checks that EDM4U has been installed when building for Android.

Troubleshooting

JDK Version Mismatch

EDM4U interacts with Android's Gradle build system, which requires precise Java JDK versions to be used. The version used should be the Unity Editor's bundled JDK version. The Unity Editor, EDM4U, and Gradle may sometimes get confused and use the current JDK version installed on the developer's computer. In this case, the resolution may fail with the following error message:

Could not initialize class org.codehaus.groovy.vmplugin.v7.Java7

This can be resolved by resetting the JDK version in Unity:

• Ensure the Unity JDK package is installed in Unity Hub.
• Navigate to Menu -> Edit -> Preferences -> External Tools -> JDK path
  • Uncheck "JDK installed with Unity (recommended)"
  • Recheck "JDK installed with Unity (recommended)"
  • Try EDM4U resolution again
  • Uncheck "JDK installed with Unity (recommended)"
  • Manually enter the Unity's built-in JDK path.
  • Try EDM4U resolution again
  • Recheck "JDK installed with Unity (recommended)"
  • Try EDM4U resolution again