@Override public void received(Consumer<T> consumer, Message<T> msg) {
      try {
        final byte[] serialized = msg.getData();
        metrics.incrementMessages();
        metrics.incrementBytes(serialized.length);

        if (serialized.length == 0) return; // lenient on empty messages

        collector.acceptSpans(serialized, NOOP);
        consumer.acknowledgeAsync(msg);
      } catch (Throwable th) {
        metrics.incrementMessagesDropped();
        LOG.error("Pulsar Span Consumer failed to process the message.", th);
        consumer.negativeAcknowledge(msg);
      }
    }
A message listener implementation for processing messages in a Pulsar consumer,
and it should not be overridden by loadConf as it ensures that zipkin could handle span correctly.
zipkin-collector/pulsar/src/main/java/zipkin2/collector/pulsar/PulsarSpanConsumer.java