void handleIncompleteRpc(V1Span source) {
    handleIncompleteRpc(first);
    for (Span.Builder span : spans) {
      handleIncompleteRpc(span);
    }
    if (source.timestamp != 0) {
      first.timestamp(source.timestamp).duration(source.duration);
    }
  }
Allows you to split a v1 span when necessary. This can be the case when reading merged
client+server spans from storage or parsing old data formats.

<p>This type isn't thread-safe: it re-uses state to avoid re-allocations in conversion loops.
zipkin/src/main/java/zipkin2/v1/V1SpanConverter.java