docs: public static SoyString checkSoyString(Object o) {
      // if it isn't a sanitized content we don't want to warn and if it isn't a soystring we should
      // always fail.
      if (o instanceof SoyString
          && o instanceof SanitizedContent
          && ((SanitizedContent) o).getContentKind() != ContentKind.TEXT
          && logger.isLoggable(Level.WARNING)) {
        logger.log(
            Level.WARNING,
            String.format(
                "Passing in sanitized content into a template that accepts only string is forbidden. "
                    + " Please modify the template to take in %s.",
                ((SanitizedContent) o).getContentKind()),
            new Exception());
      }
      return (SoyString) o;
    }