code: private Filter getFilter(final String columnFamily)
      {
          FilterList filter = filters.get(columnFamily);
          if (filter == null)
          {
              return this.filter;
          }
          if (this.filter != null)
          {
              filter.addFilter(this.filter);
          }
          return filter;
      }
docs: Gets the filter.
  
  @param columnFamily
  the column family
  @return the filter