code: private Mono<AuthenticationResult> acquireAccessTokenFromRefreshToken(String resource, String refreshToken, boolean isMultipleResourceRefreshToken) {
          String authorityUrl = this.environment().activeDirectoryEndpoint() + this.domain();
          ExecutorService executor = Executors.newSingleThreadExecutor();
          Mono<AuthenticationResult> authMono = Mono.defer(() -> {
              AuthenticationContext context;
              try {
                  context = new AuthenticationContext(authorityUrl, false, executor);
              } catch (MalformedURLException mue) {
                  throw Exceptions.propagate(mue);
              }
              if (proxy() != null) {
                  context.setProxy(proxy());
              }
              return Mono.create(callback -> context.acquireTokenByRefreshToken(
                      refreshToken,
                      clientId(),
                      resource,
                      Util.authenticationDelegate(callback)));
          });
          return authMono.doFinally(s -> executor.shutdown());
      }
docs: Refresh tokens are currently not used since we don't know if the refresh token has expired