code: public static SafeUrl sanitize(String url, Set<CustomSafeUrlScheme> extraAllowedSchemes) {
      if (!isSafeUrl(url, extraAllowedSchemes)) {
        return SafeUrl.INNOCUOUS;
      }
      return create(url);
    }
docs: Creates a SafeUrl object from the given {@code url}, validating that the input string matches
  a pattern of commonly used safe URLs. If {@code url} fails validation, this method returns a
  SafeUrl, {@link SafeUrl#INNOCUOUS}, which contains an innocuous string,
  {@link SafeUrl#INNOCUOUS_STRING}.
  
  <p>{@code url} is sanitized as in {@link #sanitize(String)}, additionally permitting the
  custom schemes listed in {@code extraAllowedSchemes}.