I need help to understand how manifest merging works

Questions
#1

I created the myextension extension as shown in the manual https://defold.com/manuals/extensions /.

AndroidManifest.xml has been created in the manifest/android folder.

The problem is that I need to substitute:

<application
android:name="android.support.multidex.MultiDexApplication"

on:

<application
android:name="com.plugin.default.MyApplication"

After reading https://defold.com/ru/manuals/extensions-manifest-merge-tool / it seems that you need to do this:

<?xml version="1.0" encoding="utf-8"?>
<!-- BEGIN_INCLUDE(manifest) -->
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        package="{{android.package}}">

    <application>
        <meta-data android:name="com.plugin.default.MyApplication"
            android:value="{{project.title}}" />
    </application>
</manifest>
<!-- END_INCLUDE(manifest) -->

But it’s over and it doesn’t work. I ask for your help.