docs: public SafeScript toSafeScript() {
      Preconditions.checkState(
          getContentKind() == ContentKind.JS,
          "toSafeScript() only valid for SanitizedContent of kind JS, is: %s",
          getContentKind());
      return UncheckedConversions.safeScriptFromStringKnownToSatisfyTypeContract(getContent());
    }