title: Android's AppCompatActivity.onMenuOpened signature expects a non null menu, but receives a null, instead
body: <p>After updating build and target sdk to 29 in my project, I see that AppCompat's Activity <code>onMenuOpened</code> <code>menu</code> parameter is annotated with <code>@RecentlyNonNull</code>.</p>
  
  <p>Previously, my overrided implementation of that method was:</p>
  
  <pre><code>override fun onMenuOpened(featureId: Int, menu: Menu?): Boolean {
      // some code
      return super.onMenuOpened(featureId, menu)
  }
  </code></pre>
  
  <p>But I'm getting this warning:</p>
  
  <pre><code>MainActivity.kt: (656, 46): Type mismatch: inferred type is Menu? but Menu was expected
  </code></pre>
  
  <p>And if I change the <code>menu: Menu?</code> parameter to be <code>menu: Menu</code> I'm getting this error in runtime</p>
  
  <pre><code>java.lang.IllegalArgumentException: Parameter specified as non-null is null: method kotlin.jvm.internal.Intrinsics.checkParameterIsNotNull, parameter menu
  </code></pre>
  
  <p>Because, in fact, it is null. As explained <a href="https://stackoverflow.com/questions/41558904/why-is-menu-of-appcompatactivity-onmenuopenedint-featureid-menu-menu-null">here</a></p>
  
  <p>I guess that this is a bug, since the system itself invokes the method with a null. Has anyone faced this issue before?</p>