code: @POST
    @Path("/report")
    @Consumes(SmileMediaTypes.APPLICATION_JACKSON_SMILE)
    public Response report(
        PushedSegmentsReport report,
        @Context final HttpServletRequest req
    )
    {
      ChatHandlers.authorizationCheck(
          req,
          Action.WRITE,
          getDataSource(),
          authorizerMapper
      );
      if (runner == null) {
        return Response.status(Response.Status.SERVICE_UNAVAILABLE).entity("task is not running yet").build();
      } else {
        runner.collectReport(report);
        return Response.ok().build();
      }
    }
docs: {@link ParallelIndexSubTask}s call this API to report the segments they've generated and pushed.