public String[] @NotNull [] getAllPropertyValues(@NotNull PsiElement element, @NotNull String propertyName) {
    final RegExpLanguageHost host = findRegExpHost(element);
    return host != null ? host.getAllPropertyValues(propertyName) : RegExpLanguageHost.EMPTY_COMPLETION_ITEMS_ARRAY;
  }
public String[] @NotNull [] getAllPropertyValues(@NotNull PsiElement element, @NotNull String propertyName)