code: @Override
      public java.util.concurrent.Future<ListRolesResult> listRolesAsync(com.amazonaws.handlers.AsyncHandler<ListRolesRequest, ListRolesResult> asyncHandler) {
  
          return listRolesAsync(new ListRolesRequest(), asyncHandler);
      }
docs: Simplified method form for invoking the ListRoles operation with an AsyncHandler.
  
  @see #listRolesAsync(ListRolesRequest, com.amazonaws.handlers.AsyncHandler)