public ZipkinExtension storeSpans(List<Span> spans) {
    try {
      storage.accept(spans).execute();
    } catch (IOException e) {
      throw new UncheckedIOException(e);
    }
    return this;
  }
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.
zipkin-junit5/src/main/java/zipkin2/junit5/ZipkinExtension.java