docs: @Default
    @Produces
    @Singleton
    public Tracer produceTracer() {
      // TCK casts to MockTracer so we cannot use GlobalTracer as a bean!
      Tracer tracer = TracerResolver.resolveTracer();
      if (tracer == null) {
        tracer = GlobalTracer.get();
      }
      logger.info(String.format("Registering %s to GlobalTracer and providing it as CDI bean.", tracer));
      GlobalTracer.register(tracer);
      return tracer;
    }