This is the code i am using right now in the proguard-project.txt
# This is a configuration file for ProGuard.
# http://proguard.sourceforge.net/index.html#m
If you're stuck with this on Android Studio, the solution of Eric must be applied to your build.grade file (at the app level). Replace:
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
with:
proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'