code: public Set<Vertex> getAllProjectsAsVertices(boolean recursive)
      {
          Set<Vertex> vertices = new LinkedHashSet<>();
          for (ProjectModel projectModel : getAllProjects(recursive))
              vertices.add(projectModel.getElement());
          return vertices;
      }
docs: Recursively crawls this {@link ProjectModelTraversal} and adds all of the {@link ProjectModel}s to a {@link Set}. The exact projects returns
  will be affected by the {@link TraversalStrategy} in use by the current traversal.
  
  This is the same as {@link ProjectModelTraversal#getAllProjects(boolean)} except that it returns a Set of vertices instead of frames.