docs: @Override
      protected String decodeParamValue(String paramName, String paramValue) {
  
          if ((paramName != null) && (paramValue != null)) {
              if (PARAM_CONTENT.equals(paramName)) {
                  // content will be always encoded in UTF-8 unicode by the editor client
                  return CmsEncoder.decode(paramValue, CmsEncoder.ENCODING_UTF_8);
              } else if (PARAM_RESOURCE.equals(paramName) || PARAM_TEMPFILE.equals(paramName)) {
                  String filename = CmsEncoder.decode(paramValue, getCms().getRequestContext().getEncoding());
                  if (PARAM_TEMPFILE.equals(paramName) || CmsStringUtil.isEmpty(getParamTempfile())) {
                      // always use value from temp file if it is available
                      setFileEncoding(getFileEncoding(getCms(), filename));
                  }
                  return filename;
              } else {
                  return CmsEncoder.decode(paramValue, getCms().getRequestContext().getEncoding());
              }
          } else {
              return null;
          }
      }