Android Data Binding: how to pass variable to include layout
<p>Google documentation says that variables may be passed into an included layout's binding from the containing layout but I can't make it work but get data binding error ****msg:Identifiers must have user defined types from the XML file. handler is missing it. 
The including XML looks like this:</p>

<pre><code>&lt;layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:bind="http://schemas.android.com/apk/res-auto"&gt;

&lt;data&gt;
    &lt;import type="com.example.FocusChangeHandler"/&gt;

    &lt;variable
        name="handler"
        type="FocusChangeHandler"/&gt;
&lt;/data&gt;

&lt;!-- Some other views  ---&gt;

   &lt;include
            android:id="@+id/inputs"
            layout="@layout/input_fields"
            bind:handler="@{handler}"/&gt;        
&lt;/layout&gt;
</code></pre>

<p>And the included XML like this: </p>

<pre><code>&lt;layout xmlns:android="http://schemas.android.com/apk/res/android"&gt;
&lt;EditText
   android:id="@+id/nameEdit"       
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"       
   android:onFocusChange="@{handler.onFocusChange}"/&gt;
&lt;/layout&gt;
</code></pre>

<p>I'm able to refer the Views from included layout through generated binding class but passing a variable just doesn't work. </p>