code: protected String error2message(IApiError err) {
  		if (err != null) {
  			StringBuilder sb = new StringBuilder(err.toString());
  			if (Str.STR.notNullOrEmpty(err.param())) {
  				sb.append(" (").append(err.param()).append(")");
  			}
  			return sb.toString();
  		}
  		return new GenericApiError().toString();
  	}
docs: Override this method to change render strategy (from enum to message)
  @param err
  @return