code: function _getCondensedForm(filter) {
          if (!_.isArray(filter)) {
              return "";
          }
  
          // Format filter in condensed form
          if (filter.length > 2) {
              return filter.slice(0, 2).join(", ") + " " +
                     StringUtils.format(Strings.FILE_FILTER_CLIPPED_SUFFIX, filter.length - 2);
          }
          return filter.join(", ");
      }
docs: Get the condensed form of the filter set by joining the first two in the set with
  a comma separator and appending a short message with the number of filters being clipped.
  @param {Array.<string>} filter
  @return {string} Condensed form of filter set if `filter` is a valid array.
  Otherwise, return an empty string.