I have to explain a few things before (partly) answering your question.
Restlet Framework provides an API and an implementation, and we try to provide them in multiple environments (classical JVM, servlet container, android, gwt, gae). As these environments supports only parts of the JDKs (GWT hates server code for example), we address this constraint by providing what we call "editions" of the framework (cf http://restlet.com/learn/guide/2.2/editions/).
In the context of the ejre, I understand that the internal server connector based on the JDK lightweight server is not supported.
In order to help you we can introduce a new edition (cf this ticket https://github.com/restlet/restlet-framework-java/issues/939).
As I'm not sure to be able to provide it shortly, I would like to know if you intend to run an HTTP server inside the JVM, or if you just want to issue client requests.
In this case, you may try to run these instructions before (not tested):
org.restlet.engine.Engine.register(false);
Engine.getInstance().getRegisteredClients().add(new org.restlet.engine.connector.HttpClientHelper(null));