code: public SafeHtml toSafeHtml() {
      Preconditions.checkState(
          getContentKind() == ContentKind.HTML,
          "toSafeHtml() only valid for SanitizedContent of kind HTML, is: %s",
          getContentKind());
      return UncheckedConversions.safeHtmlFromStringKnownToSatisfyTypeContract(getContent());
    }
docs: Converts a Soy {@link SanitizedContent} of kind HTML into a {@link SafeHtml}.
  
  @throws IllegalStateException if this SanitizedContent's content kind is not {@link
  ContentKind#HTML}.