title: Android-Binding "type" associated with an element type "variable" must not contain the '<' character
body: <p>I get the following error: <strong>The value of attribute "type" associated with an element type "variable" must not contain the '&lt;' character.</strong> </p>
  
  <p>And type="ObservableField"/> is colored red in xml.</p>
  
  <p>Any ideas?</p>
  
  <pre><code> &lt;?xml version="1.0" encoding="utf-8"?&gt;
   &lt;layout&gt;
  
  &lt;data&gt;
  
  &lt;import type="android.databinding.ObservableField"/&gt;
  &lt;variable name="field" type="ObservableField&lt;String&gt;"/&gt;
  
  &lt;/data&gt;
  
  &lt;android.support.constraint.ConstraintLayout
  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="match_parent"&gt;
  
  &lt;TextView
      android:id="@+id/textView"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_marginTop="72dp"
      android:text="@{field.get()}"
      app:layout_constraintLeft_toLeftOf="parent"
      app:layout_constraintRight_toRightOf="parent"
      app:layout_constraintTop_toTopOf="parent" /&gt;
  
  &lt;Button
      android:id="@+id/button"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_marginBottom="181dp"
      android:layout_marginEnd="149dp"
      android:layout_marginStart="147dp"
      android:layout_marginTop="191dp"
      android:text="Button"
      app:layout_constraintBottom_toBottomOf="parent"
      app:layout_constraintEnd_toEndOf="parent"
      app:layout_constraintStart_toStartOf="parent"
      app:layout_constraintTop_toBottomOf="@+id/textView" /&gt;
  
  &lt;/android.support.constraint.ConstraintLayout&gt;
  
  &lt;/layout&gt;
  </code></pre>