docs: private String obtainMatchingRedirect(Set<String> redirectUris, String requestedRedirect) {
          Assert.notEmpty(redirectUris, "Redirect URIs cannot be empty");
  
          if (redirectUris.size() == 1 && requestedRedirect == null) {
              return redirectUris.iterator().next();
          }
          for (String redirectUri : redirectUris) {
              if (requestedRedirect != null && redirectMatches(requestedRedirect, redirectUri)) {
                  return requestedRedirect;
              }
          }
          throw new RedirectMismatchException("Invalid redirect: " + requestedRedirect
                  + " does not match one of the registered values: " + redirectUris.toString());
      }