smallrye make foreach conditiont Multi quarkus

[hamedKey999]

I want to make a category tree, here is the category structure

class category{
private String id;
private String parentId;
private List children;
}
children at the beginning is empty, parentId if null is a parent otherwise it is children. I want to return this result:

[
{
"id": "61eb379e6d797574df47cfc3",

"parentId": "",

"children": [
  {
    "id": "61ea7e5f1323dd3731dd304a",
   
    "parentId": "61eb379e6d797574df47cfc3",
   
    "children": null
  },
  {
    "id": "61ea8f471323dd3731dd304c",
    "status": "PUBLISHED",
 
    "parentId": "61eb379e6d797574df47cfc3",
   
    "children": null
  }
]

}
]
I did with classic programming I want to migrate to reactive programming with mutiny smallrye here is my code:

@Blocking
public Uni<List> getAllCategories(Request doc) {
log.info("REST request to find Categories : {}", doc);
Map<String, Object> parent = new HashMap<>();

List<CategoryDto> all = categoryRepository
        .streamAllAggregators(doc).subscribe().asStream().map(it -> aggregatorMapper.categoryToCategoryDto(it, doc.getLang())).collect(toList());

List<CategoryDto> listParent = categoryRepository
        .findByParentId("").subscribe().asStream().map(it -> aggregatorMapper.categoryToCategoryDto(it, doc.getLang())).collect(toList());
List<CategoryDto> listChildren = all.stream()
        .filter(n -> n.getParentId() != null)
        .collect(Collectors.toList());
List<CategoryDto> categoryDtoList = new ArrayList<>();
for (int i = 0; i < listParent.size(); i++) {
    categoryDtoList = new ArrayList<>();
    for (int j = 0; j < listChildren.size(); j++) {
        if (listChildren.get(j).getParentId().equals(listParent.get(i).getId().toString())) {
            categoryDtoList.add(listChildren.get(j));

        }
    }
    listParent.get(i).setChildren(categoryDtoList);
}

return Uni.createFrom().item(listParent);

}

i want to delete @Blocking