RedirectAttributes not working in SpringBoot project

I am trying to set up RedirectAttributes, but nothing happens when I do so. Here is my controller:

import org.springframework.web.servlet.mvc.support.RedirectAttributes;


    @GetMapping("/run-1")
    public String getTests(RedirectAttributes redirectAttributes) {
        logger.info("Info Log in Main controller class");
        logger.info(workingDir);
        redirectAttributes.addFlashAttribute("uploadStatus", "redirectWithRedirectView");
        redirectAttributes.addAttribute("uploadStatus", "redirectWithRedirectView");
        return "redirect:uploadStatus";

    }

This is a SpringBoot project, and since it is the Umbrella over Spring MVC, then I assumed I could use RedirectAttributes. So, what is going on? When I hit this end point, I am returned: redirect:uploadStatus

Answer

@RequestMapping(value = "/session", method = RequestMethod.POST)
public String joinSession(RedirectAttributes redirectAttributes){
    /* --- */
    redirectAttributes.addFlashAttribute("error", "!!!Wrong Password!!!");
    return "redirect:/dashboard";
}