docs: @PostConstruct
      void init(TracingRunnableInstrumenter instrumenter) {
          if (instrumenter != null) {
              Func1<Action0, Action0> existing = RxJavaHooks.getOnScheduleAction();
              if (existing != null && !(existing instanceof InstrumentScheduleAction)) {
                  RxJavaHooks.setOnScheduleAction(action0 ->
                          new InstrumentScheduleAction(instrumenter).call(existing.call(action0))
                  );
              } else {
                  RxJavaHooks.setOnScheduleAction(new InstrumentScheduleAction(instrumenter));
              }
          }
      }