docs: @Override
      public void close() {
          try {
              if (future != null) {
                  if (!(future.isDone() || future.isCancelled())) {
                      boolean cancelled = future.cancel(true);
                      if (!cancelled) {
                          // On shutdown these threads are getting closed down from elsewhere
                          if (future.isDone() || future.isCancelled()) {
                              if (TraceComponent.isAnyTracingEnabled() && tc.isDebugEnabled()) {
                                  Tr.debug(tc, "PollingDynamicConfig lost race in future cancel: {0}", this);
                              }
                              // Something 'odd' happened
                          } else {
                              if (tc.isWarningEnabled()) {
                                  Tr.warning(tc, "future.update.not.cancelled.CWMCG0016E", this);
                              }
                          }
                      }
                  }
                  future = null;
              }
          } finally {
              if (this.localExecutor) {
                  this.executor.shutdown();
              }
          }
      }