code: public static MozuUrl updateExtendedPropertyUrl(String key, String responseFields, Boolean upsert)
  	{
  		UrlFormatter formatter = new UrlFormatter("/api/commerce/carts/current/extendedproperties/{key}?upsert={upsert}&responseFields={responseFields}");
  		formatter.formatUrl("key", key);
  		formatter.formatUrl("responseFields", responseFields);
  		formatter.formatUrl("upsert", upsert);
  		return new MozuUrl(formatter.getResourceUrl(), MozuUrl.UrlLocation.TENANT_POD) ;
  	}
docs: Get Resource Url for UpdateExtendedProperty
  @param key Key used for metadata defined for objects, including extensible attributes, custom attributes associated with a shipping provider, and search synonyms definitions. This content may be user-defined depending on the object and usage.
  @param responseFields Filtering syntax appended to an API call to increase or decrease the amount of data returned inside a JSON object. This parameter should only be used to retrieve data. Attempting to update data using this parameter may cause data loss.
  @param upsert Any set of key value pairs to be stored in the extended properties of a cart.
  @return   String Resource Url