code: public <V extends BasicFileAttributeView, R extends BasicFileAttributes> TwoBuilder<V, R> attributes( String name, Class<V> viewClass, Class<R> readerClass ) {
          TwoBuilder<V, R> builder = new TwoBuilder<>( name, viewClass, readerClass, this );
          provider.add( name, viewClass, readerClass, builder.two );
          return builder;
      }
docs: declares attributes where view(setter) and reader are 2 classes
  you must be able to get the reader by calling readAttributes on the view object
  this connection could only be verified by reflection, so get it right