code: public static Map<String, String> parameterMapToStringStringMap(
              Map<String, IPortletDefinitionParameter> parametersMap) {
  
          if (null == parametersMap) {
              return null;
          }
  
          Map<String, String> stringMap = new HashMap<>(parametersMap.size());
  
          for (String key : parametersMap.keySet()) {
              stringMap.put(key, parametersMap.get(key).getValue());
          }
  
          return stringMap;
      }
docs: Converts from Map String->IPortletDefinitionParameter (as offered by IPortletDefinition) to
  Map String->String (the view on these parameters that might be simplest for some uses, e.g.
  generating JSON.
  
  @param parametersMap potentially null Map from String name of parameter to
  IPortletDefinitionParameter
  @return potentially null Map from String param name to String param value
  @since uPortal 5.2