ivy cannot download org.restlet.ext.servlet jar

I checkout the project and run `ant idea`, it will try to download jars. But https://repo1.maven.org/maven2/org/restlet/jee/org.restlet.ext.servlet/2.3.0/org.restlet.ext.servlet-2.3.0.jar will return 404 now.

[ivy:retrieve] ==== public: tried
[ivy:retrieve] https://repo1.maven.org/maven2/org/restlet/jee/org.restlet.ext.servlet/2.3.0/org.restlet.ext.servlet-2.3.0.jar
[ivy:retrieve] ::::::::::::::::::::::::::::::::::::::::::::::
[ivy:retrieve] :: FAILED DOWNLOADS ::
[ivy:retrieve] :: ^ see resolution messages for details ^ ::
[ivy:retrieve] ::::::::::::::::::::::::::::::::::::::::::::::
[ivy:retrieve] :: org.restlet.jee#org.restlet;2.3.0!org.restlet.jar
[ivy:retrieve] :: org.restlet.jee#org.restlet.ext.servlet;2.3.0!org.restlet.ext.servlet.jar
[ivy:retrieve] ::::::::::::::::::::::::::::::::::::::::::::::