message: Got child fragment manager directly
diff: @@ -16,12 +16,12 @@ class FragmentNavigator extends SceneNavigator {
  @Override
  boolean canNavigate(Activity activity, NavigationStackView stack) {
  - return !getFragmentManager(stack).isStateSaved();
  + return !stack.fragment.getChildFragmentManager().isStateSaved();
  }
  @Override
  void navigateBack(int currentCrumb, int crumb, Activity activity, NavigationStackView stack) {
  - FragmentManager fragmentManager = getFragmentManager(stack);
  + FragmentManager fragmentManager = stack.fragment.getChildFragmentManager();
  SceneFragment fragment = (SceneFragment) fragmentManager.findFragmentByTag(oldKey);
  Pair[] sharedElements = fragment != null ? getOldSharedElements(currentCrumb, crumb, fragment, stack) : null;
  SceneFragment prevFragment = (SceneFragment) fragmentManager.findFragmentByTag(stack.keys.getString(crumb));
  @@ -32,7 +32,7 @@ class FragmentNavigator extends SceneNavigator {
  @Override
  void navigate(int currentCrumb, int crumb, Activity activity, NavigationStackView stack) {
  - final FragmentManager fragmentManager = getFragmentManager(stack);
  + final FragmentManager fragmentManager = stack.fragment.getChildFragmentManager();
  int enter = getAnimationResourceId(activity, stack.enterAnim, android.R.attr.activityOpenEnterAnimation);
  int exit = getAnimationResourceId(activity, stack.exitAnim, android.R.attr.activityOpenExitAnimation);
  if (exit == 0 && stack.exitAnim != null)
  @@ -75,7 +75,7 @@ class FragmentNavigator extends SceneNavigator {
  SceneView scene = stack.scenes.get(key);
  int popEnter = getAnimationResourceId(activity, scene.enterAnim, android.R.attr.activityCloseEnterAnimation);
  int popExit = getAnimationResourceId(activity, scene.exitAnim, android.R.attr.activityCloseExitAnimation);
  - FragmentManager fragmentManager = getFragmentManager(stack);
  + FragmentManager fragmentManager = stack.fragment.getChildFragmentManager();
  fragmentManager.popBackStack();
  FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
  fragmentTransaction.setCustomAnimations(enter, exit, popEnter, popExit);
  @@ -84,10 +84,6 @@ class FragmentNavigator extends SceneNavigator {
  fragmentTransaction.commit();
  }
  - private FragmentManager getFragmentManager(NavigationStackView stack) {
  - return stack.fragment.getChildFragmentManager();
  - }
  -
  private Pair[] getOldSharedElements(int currentCrumb, int crumb, SharedElementContainer sharedElementContainer, final NavigationStackView stack) {
  final HashMap<String, View> oldSharedElementsMap = getSharedElementMap(sharedElementContainer.getScene());
  final Pair[] oldSharedElements = currentCrumb - crumb == 1 ? getSharedElements(oldSharedElementsMap, stack.oldSharedElementNames) : null;
  