Duplicar el archivo local.properties.example y renombrar a local.properties.
Setear los valores correspondientes a las variables.
After making these changes, sync your project with Gradle files in Android Studio. You can do this by clicking on the "Sync Now" prompt that appears or by going to File > Sync Project with Gradle Files.
To ensure that the BuildConfig class is generated with the new fields, perform a clean build of your project. Go to Build > Clean Project and then Build > Rebuild Project.