code: public static String escapeHtmlRcdata(SoyValue value) {
      value = normalizeNull(value);
  
      if (isSanitizedContentOfKind(value, SanitizedContent.ContentKind.HTML)) {
        // We can't allow tags in the output, because that would allow safe HTML containing
        // "<textarea>" to prematurely close the textarea.
        // Instead, we normalize which is semantics preserving in RCDATA.
        return normalizeHtml(value.coerceToString());
      }
  
      return escapeHtml(value.coerceToString());
    }
docs: Converts the input to HTML suitable for use inside {@code <textarea>} by entity escaping.