public static V2SpanConverter create() {
    return new V2SpanConverter();
  }
Allows you convert a v2 span into a v1 span. This is helpful for legacy storage which still use
annotations. This shouldn't be used by new code.

<p>This type isn't thread-safe: it re-uses state to avoid re-allocations in conversion loops.
zipkin/src/main/java/zipkin2/v1/V2SpanConverter.java