void add(DimensionBindingForPath entry) {
                if (depth == entry.path().size())
                    elements.add(entry);
                else
                    children.computeIfAbsent(entry.path().get(depth),
                                             __ -> new Node(depth + 1)).add(entry);
            }
Performs action on the elements of this against all child element bindings, then returns the union of these two sets.
container-search/src/main/java/com/yahoo/search/query/profile/QueryProfileCompiler.java