code: private SpanNamer spanNamer() {
  		if (this.spanNamer == null) {
  			try {
  				this.spanNamer = this.beanFactory.getBean(SpanNamer.class);
  			}
  			catch (NoSuchBeanDefinitionException e) {
  				log.warn(
  						"SpanNamer bean not found - will provide a manually created instance");
  				return new DefaultSpanNamer();
  			}
  		}
  		return this.spanNamer;
  	}
docs: due to some race conditions trace keys might not be ready yet