How to modify proguard-android-optimize.txt with AndroidStudio 2.2?

Question

With Android Studio 2.2 and the new build system, the ProGuard files available in $ANDROID_HOME are no longer used:

2.2.0-alpha4 (2016/6/23)
...
ProGuard files returned by getDefaultProguardFile are distributed with the plugin now, the ones in $ANDROID_HOME are no longer used.

I used to use a modified version of proguard-android-optimize.txt suitable for my needs. Now, the file proguard-android-optimize.txt-2.2.2 located in <project_path>\build\intermediates\proguard-files is generated at build time.

So how can I do now, should there be a way?

Of course, I can (probably?) modify each and every project-specific .pro files to reach the same goal, but the advantage of changing proguard-android-optimize.txt was to do it once for all.

Answer 1

Add a ProGuard file to the proguardFiles property from outside of the project:

proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'),
        'proguard-rules.pro', '/path/to/proguard-optimize.pro'