@Test void dependencyLinkRoundTrip_withError() {
    DependencyLink link =
      DependencyLink.newBuilder().parent("foo").child("bar").callCount(2).errorCount(1).build();

    assertThat(parse(JsonSerializers.DEPENDENCY_LINK_PARSER,
      new String(DependencyLinkBytesEncoder.JSON_V1.encode(link), UTF_8))).isEqualTo(link);
  }
This isn't a test of what we "should" accept as a span, rather that characters that trip-up
json don't fail in SPAN_PARSER.
zipkin-storage/elasticsearch/src/test/java/zipkin2/elasticsearch/JsonSerializersTest.java