code: public ZipkinRule storeSpans(List<Span> spans) {
      try {
        storage.accept(spans).execute();
      } catch (IOException e) {
        throw Platform.get().uncheckedIOException(e);
      }
      return this;
    }
docs: Stores the given spans directly, to setup preconditions for a test.
  
  <p>For example, if you are testing what happens when instrumentation adds a child to a trace,
  you'd add the parent here.