code: public static void tagsToFilters(final Map<String, String> tags, 
        final List<TagVFilter> filters) {
      mapToFilters(tags, filters, true);
    }
docs: Converts the tag map to a filter list. If a filter already exists for a
  tag group by, then the duplicate is skipped.
  @param tags A set of tag keys and values. May be null or empty.
  @param filters A set of filters to add the converted filters to. This may
  not be null.