@Test void annotationNamedErrorDoesntIncrementErrorCount() {
    List<Span> trace = List.of(
        span("a", "b", "c", Kind.CLIENT, "foo", "bar", false)
            .toBuilder().addAnnotation(1L, "error").build()
    );

    assertThat(new DependencyLinker().putTrace(trace).link()).containsOnly(
      DependencyLink.newBuilder().parent("foo").child("bar").callCount(1L).build()
    );
  }
Tag indicates a failed span, not an annotation
zipkin/src/test/java/zipkin2/internal/DependencyLinkerTest.java