code: public static String getDateCreatedTimeRangeFilterQuery(String searchField, long startTime, long endTime) {
  
          String sStartTime = null;
          String sEndTime = null;
  
          // Convert startTime to ISO 8601 format
          if ((startTime > Long.MIN_VALUE) && (startTime < Long.MAX_VALUE)) {
              sStartTime = CmsSearchUtil.getDateAsIso8601(new Date(startTime));
          }
  
          // Convert endTime to ISO 8601 format
          if ((endTime > Long.MIN_VALUE) && (endTime < Long.MAX_VALUE)) {
              sEndTime = CmsSearchUtil.getDateAsIso8601(new Date(endTime));
          }
  
          // Build Solr range string
          final String rangeString = CmsSearchUtil.getSolrRangeString(sStartTime, sEndTime);
  
          // Build Solr filter string
          return String.format("%s:%s", searchField, rangeString);
      }
docs: Returns a time interval as Solr compatible query string.
  @param searchField the field to search for.
  @param startTime the lower limit of the interval.
  @param endTime the upper limit of the interval.
  @return Solr compatible query string.