public XintroActivityBuilder addFragments(List<IntroFragmentModel> introFragmentAttributes){
  introFragmentModelList.addAll(introFragmentAttributes);
  return this;
}

public XintroActivityBuilder addFragments ( List < IntroFragmentModel > introFragmentAttributes ) { introFragmentModelList . addAll ( introFragmentAttributes ) ; return this ; }
add introfragmentattributes to xintro activity builder .
