code: public void addFilter(final String columnFamily, Filter filter)
      {
          FilterList filterList = this.filters.get(columnFamily);
          if (filterList == null)
          {
              filterList = new FilterList();
          }
          if (filter != null)
          {
              filterList.addFilter(filter);
          }
          this.filters.put(columnFamily, filterList);
      }
docs: Adds the filter.
  
  @param columnFamily
  the column family
  @param filter
  the filter