title: NavigationView: how to insert divider without subgroup?
body: <p>How I can put a divider without title Subgroup in the new NavigationView?</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  
  &lt;menu xmlns:android="http://schemas.android.com/apk/res/android"&gt;
  
  
  &lt;group android:checkableBehavior="single"&gt;
      &lt;item
          android:id="@+id/drawer_armario"
          android:icon="@drawable/armario"
          android:title="@string/armario"  /&gt;
      &lt;item
          android:id="@+id/drawer_amigos"
          android:icon="@drawable/amigos"
          android:title="@string/amigos" /&gt;
  
  &lt;/group&gt;
  
  &lt;item android:title="Configuración"&gt;
      &lt;menu&gt;
          &lt;item
  
              android:id="@+id/drawer_ajustes"
              android:icon="@drawable/ajustes"
              android:title="@string/ajustes" /&gt;
          &lt;item
              android:id="@+id/drawer_ayuda"
              android:icon="@drawable/ayuda"
              android:title="@string/ayuda" /&gt;
          &lt;item
              android:id="@+id/drawer_sign_out"
              android:icon="@drawable/sign_out"
              android:title="@string/sign_out" /&gt;
  
      &lt;/menu&gt;
  
  &lt;/item&gt;
  </code></pre>
  
  <p></p>
  
  <p>I would like to put a line beetween amigos and ajustes items without Configuración title.</p>
  
  <p>Thanks!!!</p>