code: public List<String> getRegisteredWidgetAliases(String className) {
  
          List<String> result = new ArrayList<>();
          Iterator<Map.Entry<String, String>> i = m_widgetAliases.entrySet().iterator();
          while (i.hasNext()) {
              // key is alias name, value is class name
              Map.Entry<String, String> e = i.next();
              if (e.getValue().equals(className)) {
                  result.add(e.getKey());
              }
          }
          return result;
      }
docs: Returns the alias for the given Widget class name, may be <code>null</code> if no alias is defined for
  the class.<p>
  
  @param className the name of the widget
  @return the alias for the given Widget class name, may be <code>null</code> if no alias is defined for
  the class