recursive Collectors.groupingBy() java streams

Question

Given two simple data container classes:

@Data
@Builder
public class Category {

    private Long id;
    private String name;
    private String codename;
    private AccessibilityEnum accessibility;
    private String description;
    private List<Article> publishedQuestions;
    private List<Category> subcategories;
    private List<Article> draftQuestions;
    private String url;
    private Category parent;`  
    
@Data
@Builder
public class SearchResult {

    private Long id; //articleId
    private String name;
    private String slug;
    private List<String> tagNames;
    private String answerSample;
    private String longAnswerSample;
    private String lastPublishedUserName;
    private Boolean isPublished;
    private LocalDate lastPublishedDate;
    private Boolean isInternal;
    private Category category;
    private String url;

Now when performing a search, say we search for the word "password" and we get 10 articles back as a result, within these 10 articles (search Results) that we got back, 3 of them are from let's say HR Category, 2 of those 3 are from the employees' category, which is a sub-category of HR and the other one left is within the salary category, which is itself a sub-category of employees.

I want to have a filtering method that filters by category hierarchy, so i get something like this:

• HR (3)
-- • Employees (2)
----- • Salary (1)
• random category (4)
-- • random sub-category (1)
----- • random sub-category (3)
• another random category (3) \

This is the method that I wrote:

public Map<Category, Long> findSearchResultsHits(String query) { return findAllSearchResults(query).stream().collect(Collectors.groupingBy(SearchResult::getCategory, Collectors.counting())); }

but I only get the original category of the article, not the hierarchy.