docs: public Set<ClassDescriptor> getDirectSubtypes(ClassDescriptor classDescriptor) throws ClassNotFoundException {
  
          ClassVertex startVertex = resolveClassVertex(classDescriptor);
  
          Set<ClassDescriptor> result = new HashSet<>();
          Iterator<InheritanceEdge> i = graph.incomingEdgeIterator(startVertex);
          while (i.hasNext()) {
              InheritanceEdge edge = i.next();
              result.add(edge.getSource().getClassDescriptor());
          }
  
          return result;
      }