code: public List<IType> getMessageOrBuilderList() {
      if (externalMessageOrBuilderList == null) {
        externalMessageOrBuilderList = new MessageOrBuilderExternalList<MType, BType, IType>(this);
      }
      return externalMessageOrBuilderList;
    }
docs: Gets a view of the builder as a list of MessageOrBuilders. This returned list is live and will
  reflect any changes to the underlying builder.
  
  @return the builders in the list