Error when first root Element has no children

[ssindelar]

When the first root item (lexicographically ordered) has no children (empty folder or file) than nothing is shown.

The problem is that the FilesystemDataProvider treats the first query (parent == null) as if the first root item was the parent. If this is a file or an empty folder than nothing is return. The correct way is to return the root items.

Workaround/Fix:

public class FixedFilesystemDataProvider extends FilesystemDataProvider {

	private static final long serialVersionUID = 6219944935877634942L;

	public FixedFilesystemDataProvider(FilesystemData treeData) {
		super(treeData);
	}

	@Override
	public int getChildCount(HierarchicalQuery<File, SerializablePredicate<File>> query) {
		if(query.getParentOptional().isPresent()) {
			return (int) fetchChildren(query).count();
		} else {
			return getTreeData().getRootItems().size();
		}
	}

	@Override
	public Stream<File> fetchChildren(HierarchicalQuery<File, SerializablePredicate<File>> query) {
		if (!isInMemory()) {
			Optional<File> optParent = query.getParentOptional();
			if (optParent.isPresent()) {
				File parent = optParent.get();
				if (getTreeData().getChildren(parent).isEmpty()) {
					List<File> files = ((FilesystemData) getTreeData()).getChildrenFromFilesystem(parent);
					getTreeData().addItems(parent, files);
					return files.stream();
				} else {
					return super.fetchChildren(query);
				}
			} else {
				return getTreeData().getRootItems().stream().sorted(getSortComparator());
			}
		} else {
			return super.fetchChildren(query);
		}
	}
}