code: @Implementation
    protected void startMainActivity(ComponentName componentName, UserHandle targetUser) {
      verifyCanAccessUser(targetUser);
      verifyMainActivityInManifest(componentName);
      startedMainActivities.add(new StartedMainActivity(componentName, targetUser));
    }
docs: Simulates starting the main activity specified in the specified profile, performing the same
  security checks done by the real {@link CrossProfileApps}.
  
  <p>The most recent main activity started can be queried by {@link
  #peekNextStartedMainActivity()}.