Restlet error on new ClientResource

I’m trying to create a client interface to communicate with my Restlet service.
However, when I create a ClientResource, I get an error. How do I fix this?

Source code

import org.restlet.resource.ClientResource;

public class Client {

    public static void main(String[] args) throws Exception {

        ClientResource resource = new ClientResource("http://localhost/");
    }
}

Log

Unable to register the helper org.restlet.ext.jdbc.JdbcClientHelper

java.lang.NoClassDefFoundError: org/apache/commons/pool/ObjectPool
    at java.lang.Class.getDeclaredConstructors0(Native Method)
    at java.lang.Class.privateGetDeclaredConstructors(Class.java:2671)
    at java.lang.Class.getConstructor0(Class.java:3075)
    at java.lang.Class.getConstructor(Class.java:1825)
    at org.restlet.engine.Engine.registerHelper(Engine.java:896)
    at org.restlet.engine.Engine.registerHelpers(Engine.java:928)
    at org.restlet.engine.Engine.registerHelpers(Engine.java:968)
    at org.restlet.engine.Engine.discoverConnectors(Engine.java:654)
    at org.restlet.engine.Engine.<init>(Engine.java:491)
    at org.restlet.engine.Engine.register(Engine.java:382)
    at org.restlet.engine.Engine.register(Engine.java:368)
    at org.restlet.engine.Engine.getInstance(Engine.java:252)
    at org.restlet.data.Method.<clinit>(Method.java:337)
    at org.restlet.resource.ClientResource.<init>(ClientResource.java:396)
    at Client.main(Client.java:15)
Caused by: java.lang.ClassNotFoundException: org.apache.commons.pool.ObjectPool
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 15 more
Unable to register the helper org.restlet.ext.jetty.HttpClientHelper

java.lang.NoClassDefFoundError: org/eclipse/jetty/util/ssl/SslContextFactory
    at java.lang.Class.getDeclaredConstructors0(Native Method)
    at java.lang.Class.privateGetDeclaredConstructors(Class.java:2671)
    at java.lang.Class.getConstructor0(Class.java:3075)
    at java.lang.Class.getConstructor(Class.java:1825)
    at org.restlet.engine.Engine.registerHelper(Engine.java:896)
    at org.restlet.engine.Engine.registerHelpers(Engine.java:928)
    at org.restlet.engine.Engine.registerHelpers(Engine.java:968)
    at org.restlet.engine.Engine.discoverConnectors(Engine.java:654)
    at org.restlet.engine.Engine.<init>(Engine.java:491)
    at org.restlet.engine.Engine.register(Engine.java:382)
    at org.restlet.engine.Engine.register(Engine.java:368)
    at org.restlet.engine.Engine.getInstance(Engine.java:252)
    at org.restlet.data.Method.<clinit>(Method.java:337)
    at org.restlet.resource.ClientResource.<init>(ClientResource.java:396)
    at Client.main(Client.java:15)
Caused by: java.lang.ClassNotFoundException: org.eclipse.jetty.util.ssl.SslContextFactory
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 15 more
Unable to register the helper org.restlet.ext.lucene.SolrClientHelper

java.lang.NoClassDefFoundError: org/apache/solr/request/SolrRequestHandler
    at java.lang.Class.getDeclaredConstructors0(Native Method)
    at java.lang.Class.privateGetDeclaredConstructors(Class.java:2671)
    at java.lang.Class.getConstructor0(Class.java:3075)
    at java.lang.Class.getConstructor(Class.java:1825)
    at org.restlet.engine.Engine.registerHelper(Engine.java:896)
    at org.restlet.engine.Engine.registerHelpers(Engine.java:928)
    at org.restlet.engine.Engine.registerHelpers(Engine.java:968)
    at org.restlet.engine.Engine.discoverConnectors(Engine.java:654)
    at org.restlet.engine.Engine.<init>(Engine.java:491)
    at org.restlet.engine.Engine.register(Engine.java:382)
    at org.restlet.engine.Engine.register(Engine.java:368)
    at org.restlet.engine.Engine.getInstance(Engine.java:252)
    at org.restlet.data.Method.<clinit>(Method.java:337)
    at org.restlet.resource.ClientResource.<init>(ClientResource.java:396)
    at Client.main(Client.java:15)
Caused by: java.lang.ClassNotFoundException: org.apache.solr.request.SolrRequestHandler
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 15 more
Unable to register the helper org.restlet.ext.javamail.JavaMailClientHelper

java.lang.NoClassDefFoundError: javax/mail/NoSuchProviderException
    at java.lang.Class.getDeclaredConstructors0(Native Method)
    at java.lang.Class.privateGetDeclaredConstructors(Class.java:2671)
    at java.lang.Class.getConstructor0(Class.java:3075)
    at java.lang.Class.getConstructor(Class.java:1825)
    at org.restlet.engine.Engine.registerHelper(Engine.java:896)
    at org.restlet.engine.Engine.registerHelpers(Engine.java:928)
    at org.restlet.engine.Engine.registerHelpers(Engine.java:968)
    at org.restlet.engine.Engine.discoverConnectors(Engine.java:654)
    at org.restlet.engine.Engine.<init>(Engine.java:491)
    at org.restlet.engine.Engine.register(Engine.java:382)
    at org.restlet.engine.Engine.register(Engine.java:368)
    at org.restlet.engine.Engine.getInstance(Engine.java:252)
    at org.restlet.data.Method.<clinit>(Method.java:337)
    at org.restlet.resource.ClientResource.<init>(ClientResource.java:396)
    at Client.main(Client.java:15)
Caused by: java.lang.ClassNotFoundException: javax.mail.NoSuchProviderException
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 15 more
Unable to register the helper org.restlet.ext.httpclient.HttpClientHelper

java.lang.NoClassDefFoundError: org/apache/http/params/HttpParams
    at java.lang.Class.getDeclaredConstructors0(Native Method)
    at java.lang.Class.privateGetDeclaredConstructors(Class.java:2671)
    at java.lang.Class.getConstructor0(Class.java:3075)
    at java.lang.Class.getConstructor(Class.java:1825)
    at org.restlet.engine.Engine.registerHelper(Engine.java:896)
    at org.restlet.engine.Engine.registerHelpers(Engine.java:928)
    at org.restlet.engine.Engine.registerHelpers(Engine.java:968)
    at org.restlet.engine.Engine.discoverConnectors(Engine.java:654)
    at org.restlet.engine.Engine.<init>(Engine.java:491)
    at org.restlet.engine.Engine.register(Engine.java:382)
    at org.restlet.engine.Engine.register(Engine.java:368)
    at org.restlet.engine.Engine.getInstance(Engine.java:252)
    at org.restlet.data.Method.<clinit>(Method.java:337)
    at org.restlet.resource.ClientResource.<init>(ClientResource.java:396)
    at Client.main(Client.java:15)
Caused by: java.lang.ClassNotFoundException: org.apache.http.params.HttpParams
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 15 more
Unable to register the helper org.restlet.ext.jetty.HttpServerHelper

java.lang.NoClassDefFoundError: org/eclipse/jetty/server/Connector
    at java.lang.Class.getDeclaredConstructors0(Native Method)
    at java.lang.Class.privateGetDeclaredConstructors(Class.java:2671)
    at java.lang.Class.getConstructor0(Class.java:3075)
    at java.lang.Class.getConstructor(Class.java:1825)
    at org.restlet.engine.Engine.registerHelper(Engine.java:896)
    at org.restlet.engine.Engine.registerHelpers(Engine.java:928)
    at org.restlet.engine.Engine.registerHelpers(Engine.java:968)
    at org.restlet.engine.Engine.discoverConnectors(Engine.java:656)
    at org.restlet.engine.Engine.<init>(Engine.java:491)
    at org.restlet.engine.Engine.register(Engine.java:382)
    at org.restlet.engine.Engine.register(Engine.java:368)
    at org.restlet.engine.Engine.getInstance(Engine.java:252)
    at org.restlet.data.Method.<clinit>(Method.java:337)
    at org.restlet.resource.ClientResource.<init>(ClientResource.java:396)
    at Client.main(Client.java:15)
Caused by: java.lang.ClassNotFoundException: org.eclipse.jetty.server.Connector
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 15 more
Unable to register the helper org.restlet.ext.jetty.HttpsServerHelper

java.lang.NoClassDefFoundError: org/eclipse/jetty/server/Connector
    at java.lang.Class.getDeclaredConstructors0(Native Method)
    at java.lang.Class.privateGetDeclaredConstructors(Class.java:2671)
    at java.lang.Class.getConstructor0(Class.java:3075)
    at java.lang.Class.getConstructor(Class.java:1825)
    at org.restlet.engine.Engine.registerHelper(Engine.java:896)
    at org.restlet.engine.Engine.registerHelpers(Engine.java:928)
    at org.restlet.engine.Engine.registerHelpers(Engine.java:968)
    at org.restlet.engine.Engine.discoverConnectors(Engine.java:656)
    at org.restlet.engine.Engine.<init>(Engine.java:491)
    at org.restlet.engine.Engine.register(Engine.java:382)
    at org.restlet.engine.Engine.register(Engine.java:368)
    at org.restlet.engine.Engine.getInstance(Engine.java:252)
    at org.restlet.data.Method.<clinit>(Method.java:337)
    at org.restlet.resource.ClientResource.<init>(ClientResource.java:396)
    at Client.main(Client.java:15)
Caused by: java.lang.ClassNotFoundException: org.eclipse.jetty.server.Connector
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 15 more
Unable to register the helper org.restlet.ext.simple.HttpServerHelper

java.lang.NoClassDefFoundError: org/simpleframework/http/core/Container
    at java.lang.Class.getDeclaredConstructors0(Native Method)
    at java.lang.Class.privateGetDeclaredConstructors(Class.java:2671)
    at java.lang.Class.getConstructor0(Class.java:3075)
    at java.lang.Class.getConstructor(Class.java:1825)
    at org.restlet.engine.Engine.registerHelper(Engine.java:896)
    at org.restlet.engine.Engine.registerHelpers(Engine.java:928)
    at org.restlet.engine.Engine.registerHelpers(Engine.java:968)
    at org.restlet.engine.Engine.discoverConnectors(Engine.java:656)
    at org.restlet.engine.Engine.<init>(Engine.java:491)
    at org.restlet.engine.Engine.register(Engine.java:382)
    at org.restlet.engine.Engine.register(Engine.java:368)
    at org.restlet.engine.Engine.getInstance(Engine.java:252)
    at org.restlet.data.Method.<clinit>(Method.java:337)
    at org.restlet.resource.ClientResource.<init>(ClientResource.java:396)
    at Client.main(Client.java:15)
Caused by: java.lang.ClassNotFoundException: org.simpleframework.http.core.Container
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 15 more
Unable to register the helper org.restlet.ext.simple.HttpsServerHelper

java.lang.NoClassDefFoundError: org/simpleframework/http/core/Container
    at java.lang.Class.getDeclaredConstructors0(Native Method)
    at java.lang.Class.privateGetDeclaredConstructors(Class.java:2671)
    at java.lang.Class.getConstructor0(Class.java:3075)
    at java.lang.Class.getConstructor(Class.java:1825)
    at org.restlet.engine.Engine.registerHelper(Engine.java:896)
    at org.restlet.engine.Engine.registerHelpers(Engine.java:928)
    at org.restlet.engine.Engine.registerHelpers(Engine.java:968)
    at org.restlet.engine.Engine.discoverConnectors(Engine.java:656)
    at org.restlet.engine.Engine.<init>(Engine.java:491)
    at org.restlet.engine.Engine.register(Engine.java:382)
    at org.restlet.engine.Engine.register(Engine.java:368)
    at org.restlet.engine.Engine.getInstance(Engine.java:252)
    at org.restlet.data.Method.<clinit>(Method.java:337)
    at org.restlet.resource.ClientResource.<init>(ClientResource.java:396)
    at Client.main(Client.java:15)
Caused by: java.lang.ClassNotFoundException: org.simpleframework.http.core.Container
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 15 more
Unable to register the helper org.restlet.ext.jibx.JibxConverter

java.lang.NoClassDefFoundError: org/jibx/runtime/JiBXException
    at java.lang.Class.getDeclaredConstructors0(Native Method)
    at java.lang.Class.privateGetDeclaredConstructors(Class.java:2671)
    at java.lang.Class.getConstructor0(Class.java:3075)
    at java.lang.Class.newInstance(Class.java:412)
    at org.restlet.engine.Engine.registerHelper(Engine.java:894)
    at org.restlet.engine.Engine.registerHelpers(Engine.java:928)
    at org.restlet.engine.Engine.registerHelpers(Engine.java:968)
    at org.restlet.engine.Engine.discoverConverters(Engine.java:667)
    at org.restlet.engine.Engine.<init>(Engine.java:495)
    at org.restlet.engine.Engine.register(Engine.java:382)
    at org.restlet.engine.Engine.register(Engine.java:368)
    at org.restlet.engine.Engine.getInstance(Engine.java:252)
    at org.restlet.data.Method.<clinit>(Method.java:337)
    at org.restlet.resource.ClientResource.<init>(ClientResource.java:396)
    at Client.main(Client.java:15)
Caused by: java.lang.ClassNotFoundException: org.jibx.runtime.JiBXException
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 15 more
Unable to register the helper org.restlet.ext.xstream.XstreamConverter

java.lang.NoClassDefFoundError: com/thoughtworks/xstream/io/json/JettisonMappedXmlDriver
    at org.restlet.ext.xstream.XstreamConverter.<init>(XstreamConverter.java:95)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
    at java.lang.Class.newInstance(Class.java:442)
    at org.restlet.engine.Engine.registerHelper(Engine.java:894)
    at org.restlet.engine.Engine.registerHelpers(Engine.java:928)
    at org.restlet.engine.Engine.registerHelpers(Engine.java:968)
    at org.restlet.engine.Engine.discoverConverters(Engine.java:667)
    at org.restlet.engine.Engine.<init>(Engine.java:495)
    at org.restlet.engine.Engine.register(Engine.java:382)
    at org.restlet.engine.Engine.register(Engine.java:368)
    at org.restlet.engine.Engine.getInstance(Engine.java:252)
    at org.restlet.data.Method.<clinit>(Method.java:337)
    at org.restlet.resource.ClientResource.<init>(ClientResource.java:396)
    at Client.main(Client.java:15)
Caused by: java.lang.ClassNotFoundException: com.thoughtworks.xstream.io.json.JettisonMappedXmlDriver
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 17 more
Unable to register the helper org.restlet.ext.javamail.JavaMailConverter

java.lang.NoClassDefFoundError: javax/mail/MessagingException
    at java.lang.Class.getDeclaredConstructors0(Native Method)
    at java.lang.Class.privateGetDeclaredConstructors(Class.java:2671)
    at java.lang.Class.getConstructor0(Class.java:3075)
    at java.lang.Class.newInstance(Class.java:412)
    at org.restlet.engine.Engine.registerHelper(Engine.java:894)
    at org.restlet.engine.Engine.registerHelpers(Engine.java:928)
    at org.restlet.engine.Engine.registerHelpers(Engine.java:968)
    at org.restlet.engine.Engine.discoverConverters(Engine.java:667)
    at org.restlet.engine.Engine.<init>(Engine.java:495)
    at org.restlet.engine.Engine.register(Engine.java:382)
    at org.restlet.engine.Engine.register(Engine.java:368)
    at org.restlet.engine.Engine.getInstance(Engine.java:252)
    at org.restlet.data.Method.<clinit>(Method.java:337)
    at org.restlet.resource.ClientResource.<init>(ClientResource.java:396)
    at Client.main(Client.java:15)
Caused by: java.lang.ClassNotFoundException: javax.mail.MessagingException
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 15 more