Android calligraphy library: set default font does not work

I did used uk.co.chrisjenx:calligraphy dependency to use fonts from asset folder, however default font is not applied to my application. I followed the guideline used in other stackoverflow question but they did not work and all solutions used same syntax I used below.

Here is my application and path to font is correct since it works using XML fontpath property;

public class App extends MultiDexApplication {

    private static volatile Context instance;

    public static Context get() {
        return instance;
    }
    private static App enableMultiDex;
    public static Context context;

    public App(){
        enableMultiDex=this;
    }
    public static App getEnableMultiDexApp() {
        return enableMultiDex;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        context = getApplicationContext();
        instance = getApplicationContext();
        Thread.setDefaultUncaughtExceptionHandler(new ExceptionHandler(this));
        CalligraphyConfig.initDefault(new CalligraphyConfig.Builder()
                .setDefaultFontPath("fonts/mobilefont.ttf")
                .setFontAttrId(R.attr.fontPath)
                .build());
    }

}

Wrap the Activity Context:

@Override
protected void attachBaseContext(Context newBase) {
    super.attachBaseContext(CalligraphyContextWrapper.wrap(newBase));
}