title: how to import public static field from class in android data binding
body: <p>I want to import some string from interface constant in android layout data binding. </p>
  
  <p>Gradle build fails if i use this line </p>
  
  <pre><code>android:drawableRight="@{item.icon.equalsIgnoreCase(Constants.FOOD_TYPE_NON_VEG)? @drawable/ic_nonveg : @drawable/ic_veg}"
  </code></pre>
  
  <p>But below line works </p>
  
  <pre><code>android:drawableRight="@{item.icon.equalsIgnoreCase(`nonveg`)? @drawable/ic_nonveg : @drawable/ic_veg}"
  </code></pre>
  
  <p>Sample xml is </p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;layout xmlns:android="http://schemas.android.com/apk/res/android"&gt;
  
      &lt;data&gt;
  
          &lt;variable
              name="Constants"
              type="com.amelio.utils.Constants"/&gt;
  
      &lt;/data&gt;
  
      &lt;TextView
          style="@style/tvVerySmall"
          android:layout_width="match_parent"
          android:drawableRight="@{item.icon.equalsIgnoreCase(`nonveg`)? @drawable/ic_nonveg : @drawable/ic_veg}"
          /&gt;
  
  &lt;/layout&gt;
  </code></pre>
  
  <p>and Constants interface is </p>
  
  <pre><code>public interface Constants {
      String FOOD_TYPE_NON_VEG  = "nonveg";
  }
  </code></pre>
  
  <p><strong>How to import string from interface in xml layout in databinding?</strong></p>