Keep classes that use Android Proguard reflection

Question

I am trying to use this class. It works great with debug builds, but never works on versions. I know that proguard removes it, so the question is: how to save this class?

import android.support.design.internal.BottomNavigationItemView;
import android.support.design.internal.BottomNavigationMenuView;
import android.support.design.widget.BottomNavigationView;
import android.util.Log;
import java.lang.reflect.Field;

public class BottomNavigationViewHelper {
    public static void disableShiftMode(BottomNavigationView view) {
        BottomNavigationMenuView menuView = (BottomNavigationMenuView) view.getChildAt(0);
        try {
            Field shiftingMode = menuView.getClass().getDeclaredField("mShiftingMode");
            shiftingMode.setAccessible(true);
            shiftingMode.setBoolean(menuView, false);
            shiftingMode.setAccessible(false);
            for (int i = 0; i < menuView.getChildCount(); i++) {
                BottomNavigationItemView item = (BottomNavigationItemView) menuView.getChildAt(i);
                //noinspection RestrictedApi 
                item.setShiftingMode(false);
                // set once again checked value, so view will be updated 
                //noinspection RestrictedApi 
                item.setChecked(item.getItemData().isChecked());
            }
        } catch (NoSuchFieldException e) {
            Log.e("BNVHelper", "Unable to get shift mode field", e);
        } catch (IllegalAccessException e) {
            Log.e("BNVHelper", "Unable to change value of shift mode", e);
        }
    }
} 

Answer 1

It helps me.

# Bottom Navigation Helper
-keep class android.support.design.internal.BottomNavigationItemView{ *; }
-keep class android.support.design.internal.BottomNavigationMenuView{ *; }

Answer 2

to save class

-keep class com.example.** { *; }

to save the attribute

-keepclassmembers class com.example.** { <fields>; }