private boolean annotationAppliesToFields(TypeElement annotation) {
    Target target = annotation.getAnnotation(Target.class);
    return target == null || Arrays.asList(target.value()).contains(ElementType.FIELD);
  }
Returns the fully-qualified name of an annotation-mirror, e.g.
"com.google.auto.value.AutoValue".
value/src/main/java/com/google/auto/value/processor/AutoValueishProcessor.java