code: protected void setNonDeferrableScheduledExecutor(ServiceReference<ScheduledExecutorService> ref) {
          if (TraceComponent.isAnyTracingEnabled() && tc.isDebugEnabled())
              Tr.debug(tc, "setNonDeferrableScheduledExecutor", ref);
          nonDeferrableSchedXSvcRef.setReference(ref);
      }
docs: Declarative Services method for setting the non-deferrable scheduled executor service reference.
  
  @param ref reference to the service