onBackPressedDispatcher-1.java

class OnBackPressedDispatcher ... {
  ...
  
  @MainThread
  public void onBackPressed() {
      Iterator<OnBackPressedCallback> iterator =
              mOnBackPressedCallbacks.descendingIterator();
      while (iterator.hasNext()) {
          OnBackPressedCallback callback = iterator.next();
          if (callback.isEnabled()) {
              callback.handleOnBackPressed();
              return;
          }
      }
      if (mFallbackOnBackPressed != null) {
          mFallbackOnBackPressed.run();
      }
  }
  
  ...
}