code: public String addPostRunDependent(FunctionalTaskItem dependent) {
          Objects.requireNonNull(dependent);
          return this.taskGroup().addPostRunDependent(dependent);
      }
docs: Add a "post-run" dependent task item for this task item.
  
  @param dependent the "post-run" dependent task item.
  @return key to be used as parameter to taskResult(string) method to retrieve result of root
  task in the given dependent task group