static HighlightInfo.@Nullable Builder checkInitializersInImplicitClass(@NotNull PsiClassInitializer initializer) {
    if (initializer.getContainingClass() instanceof PsiImplicitClass && PsiUtil.isAvailable(JavaFeature.IMPLICIT_CLASSES, initializer)) {
      return HighlightInfo.newHighlightInfo(HighlightInfoType.ERROR)
        .range(initializer)
        .descriptionAndTooltip(JavaErrorBundle.message("error.initializers.are.not.allowed.in.implicit.classes"))
        .registerFix(QuickFixFactory.getInstance().createDeleteFix(initializer), null, null, null, null);
    }
    return null;
  }
static HighlightInfo.@Nullable Builder checkInitializersInImplicitClass(@NotNull PsiClassInitializer initializer)