@Override public int hashCode() {
      int h$ = 1;
      h$ *= 1000003;
      h$ ^= (int) (h$ ^ ((timestamp >>> 32) ^ timestamp));
      h$ *= 1000003;
      h$ ^= key.hashCode();
      h$ *= 1000003;
      h$ ^= value.hashCode();
      return h$;
    }
Mutable type used for each call to store spans
zipkin-storage/elasticsearch/src/main/java/zipkin2/elasticsearch/ElasticsearchSpanConsumer.java