app/src/main/res/layout/nav_section_item.xml

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="16dp"
    android:background="@android:color/transparent"
    android:orientation="vertical">

    <View
        android:layout_width="match_parent"
        android:layout_height="1dp"
        android:layout_centerVertical="true"
        android:background="?android:attr/listDivider"
        tools:background="@android:color/holo_red_dark"/>
</RelativeLayout>