code: public static Set<ClassNode> collectAllInterfaces(ClassNode node) {
          HashSet<ClassNode> result = new HashSet<ClassNode>();
          collectAllInterfaces(node, result);
          return result;
      }
docs: Collects all interfaces of a class node, including those defined by the
  super class.
  @param node a class for which we want to retrieve all interfaces
  @return a set of interfaces implemented by this class node