@Override protected void doEnqueue(Callback<Void> callback) {
        if (counter.getAndIncrement() == 1) {
          callback.onError(new RuntimeException("storage fell over"));
        } else {
          receivedSpans.add(spans);
          callback.onSuccess(null);
        }
      }
Guards against errors that leak from storage, such as InvalidQueryException
zipkin-collector/activemq/src/test/java/zipkin2/collector/activemq/ITActiveMQCollector.java