static Set<String> getExcludedAnnotationClassNames(Element element) {
    return getExcludedAnnotationTypes(element).stream()
        .map(MoreTypes::asTypeElement)
        .map(typeElement -> typeElement.getQualifiedName().toString())
        .collect(toSet());
  }
Returns the contents of the {@code AutoValue.CopyAnnotations.exclude} element, as a set of
strings that are fully-qualified class names.
value/src/main/java/com/google/auto/value/processor/AutoValueishProcessor.java