title: Android Cannot anchor FAB button to BottomSheet
body: <p>I'm trying to attach a FAB button to the BottomSheet view like Google Maps does. However I cannot make it work, </p>
  
  <p>this is the code of the FAB button:</p>
  
  <pre><code> &lt;android.support.design.widget.FloatingActionButton
      android:id="@+id/fab"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_margin="@dimen/fab_margin"
      android:src="@android:drawable/ic_dialog_email"
      app:layout_anchor="@+id/nestedscrollview" --&gt; BottomSheet view ID
      app:layout_anchorGravity="bottom|end"
      app:elevation="4dp"
      /&gt;
  </code></pre>
  
  <p>and this is the code of the BottomSheet View</p>
  
  <pre><code>&lt;android.support.v4.widget.NestedScrollView
  android:id="@+id/nestedscrollview"
  xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:app="http://schemas.android.com/apk/res-auto"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  app:layout_behavior="android.support.design.widget.BottomSheetBehavior"
  tools:context="com.pub.uac.ui.location.LocationActivity"
  android:background="@color/background_white_trasnparent"
   &gt; 
  ... 
  &lt;/...
  </code></pre>