title: Lint Error: Suspicious equality check: equals() is not implemented in Object DiffUtilEquals
body: <p>It seems Android Studio/Gradle 3.4 has introduced a new lint error <code>DiffUtilEquals</code>. It is triggered by having a <code>DiffUtil&lt;Any&gt;</code> and then calling as a fallback <code>oldItem == newItem</code> in the <code>areContentsTheSame</code> function. The error the linter throws is </p>
  
  <pre class="lang-none prettyprint-override"><code>Suspicious equality check: equals() is not implemented in Object
  </code></pre>
  
  <p>Example code:</p>
  
  <pre><code> override fun areContentsTheSame(oldItem: Any, newItem: Any): Boolean {
          return when {
              oldItem is MyKotlinClass &amp;&amp; newItem is MyKotlinClass -&gt; true
              oldItem is MyKotlinClass2 &amp;&amp; newItem is MyKotlinClass2 -&gt; oldItem.title == newItem.title
              else -&gt; oldItem == newItem // Lint error on this line
          }
      }
  </code></pre>
  
  <p>This when statement would be pretty common in a DiffUtil for an Adapter that has multiple types where you compare each type based on their class.</p>
  
  <p>What is the best way to handle this error? Should <code>&lt;Any&gt;</code> be changed to some interface that is like <code>Equatable</code> or maybe all the classes used in the adapter should implement some interface that includes a way to compare them?</p>