docs: public Map<String,Object> handleUpdateFilterMap(Map<String,Object> propFilter)
      {
          if (propFilter != null)
          {
              Object bookmark = propFilter.get(ADD_BOOKMARK);
              if (bookmark != null)
              {
                  if (CLEAR_BOOKMARKS.equals(bookmark))
                  {
                  	if (m_htBookmarks != null)
                  		m_htBookmarks.clear();
                      m_strSecondaryKey = null;             // The secondary key to watch for.
                      m_objKeyData = null;                  // The reference value to watch for.
                      String strHint = (String)propFilter.get(SECOND_KEY_HINT);
                      if (strHint != null)
                      {
                          Object objKeyData = propFilter.get(strHint);    // The value of the 2nd key reference data.
                          m_strSecondaryKey = strHint;                    // The secondary key to watch for.
                          m_objKeyData = objKeyData;                      // The reference value to watch for.
                      }
                  }
                  else
                  {
                  	if (m_htBookmarks != null)
                  		if (!m_htBookmarks.contains(bookmark))
                  			m_htBookmarks.add(bookmark);
                  }
              }
          }
          return super.handleUpdateFilterMap(propFilter);   // Update any remote copy of this.
      }