private static @Nullable Set<TargetType> calcAnnotationTargets(PsiModifierList modifierList) {
    PsiAnnotation target = modifierList.findAnnotation(CommonClassNames.JAVA_LANG_ANNOTATION_TARGET);
    if (target == null) return DEFAULT_TARGETS;  // if omitted it is applicable to all but Java 8 TYPE_USE/TYPE_PARAMETERS targets

    PsiNameValuePair attribute = AnnotationUtil.findDeclaredAttribute(target, null);
    if (attribute == null) return null;

    return extractRequiredAnnotationTargets(attribute.getDetachedValue());
  }
private static @Nullable Set<TargetType> calcAnnotationTargets(PsiModifierList modifierList)