src/vs/workbench/contrib/comments/browser/commentsTreeViewer.ts/Filter/filter
class Filter:	filter(element: ResourceWithCommentThreads | CommentNode, parentVisibility: TreeVisibility): TreeFilterResult<FilterData> {
		if (element instanceof ResourceWithCommentThreads) {
			return this.filterResourceMarkers(element);
		} else {
			return this.filterCommentNode(element, parentVisibility);
		}
	}