docs: public static MultiDataSetIterator getMultiIterator(Object o) {
          if (o instanceof MultiDataSetIterator) {
              return (MultiDataSetIterator) o;
          } else if (o instanceof MultiDataSetIteratorFactory) {
              MultiDataSetIteratorFactory factory = (MultiDataSetIteratorFactory) o;
              return factory.create();
          } else if( o instanceof DataSetIterator ){
              return new MultiDataSetIteratorAdapter((DataSetIterator)o);
          } else if( o instanceof DataSetIteratorFactory ){
              return new MultiDataSetIteratorAdapter(((DataSetIteratorFactory)o).create());
          }
  
          throw new IllegalArgumentException("Type must either be DataSetIterator or DataSetIteratorFactory");
      }