layout_group.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <include
            layout="@layout/layout_appbar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />

        <androidx.recyclerview.widget.RecyclerView
            android:id="@+id/group_list"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:padding="4dp"
            android:scrollbarSize="0dp" />

    </LinearLayout>

</androidx.coordinatorlayout.widget.CoordinatorLayout>