protected TwoLevelExpandableAdapter(List<T> data){
  fullData=data;
  dataList=new ArrayList<>();
  isOpen=new ArrayList<>();
  for (  T item : fullData) {
    dataList.add(new DataHolder(item.getData(),ItemType.HEADER));
    isOpen.add(false);
  }
}

protected TwoLevelExpandableAdapter ( List < T > data ) { fullData = data ; dataList = new ArrayList < > ( ) ; isOpen = new ArrayList < > ( ) ; for ( T item : fullData ) { dataList . add ( new DataHolder ( item . getData ( ) , ItemType . HEADER ) ) ; isOpen . add ( false ) ; } }
return adapter with collapsed content ;
