code: function(record, extraNames) {
        var fieldNames = record.getFields().map(function (field) {
          return field.getName();
        });
  
        if (extraNames) {
          fieldNames = fieldNames.concat(extraNames);
        }
        return fieldNames;
      }
docs: actually getFields returns not all fields. So these are names for additional fields.
  @param record
  @param extraNames
  
  @return {Array}