applyNotFoundIndicators = function (translationId) {
        // applying notFoundIndicators
        if ($notFoundIndicatorLeft) {
          translationId = [$notFoundIndicatorLeft, translationId].join(' ');
        }
        if ($notFoundIndicatorRight) {
          translationId = [translationId, $notFoundIndicatorRight].join(' ');
        }
        return translationId;
      }
@name applyNotFoundIndicators
@private

@description
Applies not fount indicators to given translation id, if needed.
This function gets only executed, if a translation id doesn't exist,
which is why a translation id is expected as argument.

@param {string} translationId Translation id.
@returns {string} Same as given translation id but applied with not found
indicators.