There's not a whole lot of risk here because of the limited surface area of Restlet in the project. Ishan Chattopadhyaya even suggested we could remove it, which I tend to agree with.
I noticed that the Restlet dependency's location was no longer resolving at: https://repo1.maven.org/maven2/org/restlet/jee/org.restlet/2.4.0/org.restlet-2.4.0.jar.
Now, of course, I could change it to a location that does resolve or download directly. However, I looking at the changelog I thought that maybe I should raise with the community that it an upgrade might be helpful given the CVEs.
I will leave it to the experts as to whether it makes a difference, but here's the changelog for reference.
The Lucene tests passed when I upgraded to 2.4.3 but I'm still digging in. It is very likely that 2.4.1 would be better. I'd leave that, again, to the experts and post my findings.