code: public void feedTheWholeTagStructureToGraph(org.jboss.windup.config.tags.TagService tagLoaderService)
      {
  
          Set<Tag> visited = new HashSet<>();
  
          for (Tag tag : tagLoaderService.getRootTags())
          {
              // Sanity check
              TagModel existing = this.getUniqueByProperty(TagModel.PROP_NAME, tag.getName());
              if (null != existing)
              {
                  LOG.warning("TagModel already exists in graph, skipping root Tag: " + tag.getName());
                  return;
              }
  
              int level = 0;
              this.feedTagStructureToGraph(tag, visited, level);
          }
      }
docs: Traverses the graph structure and stores all tags to the graph.
  <p>
  There may be several isolated tag structures so we need to iterate through the root tags.