Bug: sometimes can't get any correct app-icon

[AndroidDeveloperLB]

See this APK for example:

base.zip

It's supposed to be as such:

But, it has only 2 icons that it returns me when calling ApkFile(filePath).allIcons :
0 = {Icon@9908} "Icon{path='res/xm.png', density=0, size=4716}"
This image is just this one:

1 = {AdaptiveIcon@9909} "AdaptiveIcon{foreground=null, background=null}"
For some reason I can't find the path right away, so what I did is to get apkMetaTranslator.iconPaths.
So, the matching IconPath for it is IconPath{path='res/uG.xml', density=0}
I used this online tool, and got this content:

<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:aapt="http://schemas.android.com/aapt">
    <background>
        <bitmap android:src="@mipmap/adaptiveproduct_one_background_color_108"/>
    </background>
    <foreground>
        <bitmap android:src="@mipmap/adaptiveproduct_one_foreground_color_108"/>
    </foreground>
</adaptive-icon>

This file doesn't exist in the folders, but somehow it exists inside somewhere else, probably in "resources.arsc".
I've found the file using both of these tools:

http://www.javadecompilers.com/apk
http://www.javadecompilers.com/apktool

This is what I got, here .

How could it be?
Opening the APK as a ZIP file doesn't show those files. But, I can see a file called "fV" in "res" folder which takes quite a lot, and I think it's the one that holds the extra content.