code: protected void configureAdditionMode(Fragment frag, int flags, FragmentTransaction ft, int containerId) {
          if ((flags & DO_NOT_REPLACE_FRAGMENT) != DO_NOT_REPLACE_FRAGMENT) {
              ft.replace(containerId, frag, ((FraggleFragment) frag).getFragmentTag());
          } else {
              ft.add(containerId, frag, ((FraggleFragment) frag).getFragmentTag());
              peek().onFragmentNotVisible();
          }
      }
docs: Configures the way to add the Fragment into the transaction. It can vary from adding a new fragment,
  to using a previous instance and refresh it, or replacing the last one.
  
  @param frag        Fragment to add
  @param flags       Added flags to the Fragment configuration
  @param ft          Transaction to add the fragment
  @param containerId Target container ID