Suppress new spotbugs warning (jenkinsci#11283)

* Suppress new spotbugs warning

* Fix checkstyle warning

---------

Co-authored-by: Mark Waite <mark.earl.waite@gmail.com>

Author: timja

core/src/main/java/hudson/slaves/SlaveComputer.java

@@ -625,6 +625,7 @@ static class LoadingTime extends MasterToSlaveCallable<Long, RuntimeException> {
      * @param listener Channel event listener to be attached (if not {@code null})
      * @since 1.444
      */
+    @SuppressFBWarnings(value = "NN_NAKED_NOTIFY", justification = "False positive, the warning isn't for this scenario")
     public void setChannel(@NonNull Channel channel,
                            @CheckForNull OutputStream launchLog,
                            @CheckForNull Channel.Listener listener) throws IOException, InterruptedException {