linphone-android/app/src/main/res/layout/activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<layout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <data>
        <import type="android.view.View" />
    </data>

    <androidx.coordinatorlayout.widget.CoordinatorLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@color/primary_color"
        tools:context=".ui.MainActivity">

        <androidx.constraintlayout.widget.ConstraintLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <androidx.fragment.app.FragmentContainerView
                android:id="@+id/main_nav_host_fragment"
                android:name="androidx.navigation.fragment.NavHostFragment"
                android:layout_width="match_parent"
                android:layout_height="0dp"
                app:defaultNavHost="true"
                app:layout_constraintTop_toTopOf="parent"
                app:layout_constraintBottom_toBottomOf="parent"
                app:navGraph="@navigation/main_nav_graph"/>

        </androidx.constraintlayout.widget.ConstraintLayout>

    </androidx.coordinatorlayout.widget.CoordinatorLayout>

</layout>