code: @FFDCIgnore(IllegalStateException.class)
      public synchronized void removeShutdownHook() {
          if (shutdownInvoked)
              return;
  
          try {
              if (hookSet.compareAndSet(true, false)) {
                  Runtime.getRuntime().removeShutdownHook(this);
              }
          } catch (IllegalStateException e) {
              // ok. based on timing, if we start shutting down, we may
              // not be able to remove the hook.
          }
      }
docs: Remove the shutdown hook from the VM (FeatureManager.deactivate)
  
  @see {@link Runtime#addShutdownHook(Thread)}
  @see {@link Runtime#removeShutdownHook(Thread)}