When portlet example is invoked from json ws api doc pages, it fails. This happens because URL is wrongly created.
The core issue is in this file: portal\portal-web\docroot\html\portal\api\jsonws\action.jsp
in the following block (line #344):
As you see, context path and action path are joined, but this is wrong. For example, instead of the correct url:
the wrong one is invoked:
Liferay.Service should add support for context, i.e. for plugins.