build failing on play-services:11.8.x with pro guard parser error

It seems the default shrinker has changed. Adding the configuration to turn on ProGuard seemed to work.

buildTypes {
        release {
            debuggable false
            minifyEnabled true
            useProguard true
            ...
        }
        debug {
            debuggable true
            minifyEnabled true
            useProguard true
            ...
        }
    }