SupportRequestManagerFragment getSupportRequestManagerFragment(final FragmentManager fm) {
        SupportRequestManagerFragment current = (SupportRequestManagerFragment) fm.findFragmentByTag(


            FRAGMENT_TAG);
        if (current == null) {
            current = pendingSupportRequestManagerFragments.get(fm);
            if (current == null) {
                current = new SupportRequestManagerFragment();
                pendingSupportRequestManagerFragments.put(fm, current);
                fm.beginTransaction().add(current, FRAGMENT_TAG).commitAllowingStateLoss();
                handler.obtainMessage(ID_REMOVE_SUPPORT_FRAGMENT_MANAGER, fm).sendToTarget();
            }
        }
        return current;
    }
Retrieves and returns the RequestManagerRetriever singleton.
core/src/main/java/com/bumptech/glide/manager/RequestManagerRetriever.java