Try this:
In addition to the standard Restlet jar files, you also need to reference jar files for HTTPS. The 'Simple' HTTPS connector uses these jar files:
lib/com.noelios.restlet.ext.simple_3.1.jar
lib/org.simpleframework_3.1/org.simpleframework.jar
lib/com.noelios.restlet.ext.ssl.jar
lib/org.jsslutils_0.5/org.jsslutils.jar
found here:http://restlet.org/learn/guide/2.2/core/security/https