Does Restlet actually work with GWT 2.4

Question

I have a backend running on Google App Engine with Objectify and have started trying to add REST web services to it. I've read nothing but good things about Restlet so i decided to start there - i looked at the first application example and got through it - got everything set up and then finally i hit an issue on the client side with the following:

private final UserResourceProxy userResourceProxy = GWT.create(UserResourceProxy.class);

where UserResourceProxy is the following

import org.restlet.client.resource.ClientProxy;
import org.restlet.client.resource.Delete;
import org.restlet.client.resource.Get;
import org.restlet.client.resource.Put;
import org.restlet.client.resource.Result;

import com.exposure101.lifelogger.shared.entity.User;

public interface UserResourceProxy extends ClientProxy {

  @Get
  public void find(String emailAddress, Result<User> callback);

  @Put
  public void persist(User user, Result<User> callback);

  @Delete
  public void delete(Result<Void> callback);
}

Here's the stack trace I get - it seems like it has no idea how to create a ClientProxy in GWT 2.4

java.lang.RuntimeException: Deferred binding failed for 'com.exposure101.lifelogger.client.rest.proxy.UserResourceProxy' (did you forget to inherit a required module?)
  at com.google.gwt.dev.shell.GWTBridgeImpl.create(GWTBridgeImpl.java:53)
  at com.google.gwt.core.client.GWT.create(GWT.java:97)
  at com.exposure101.lifelogger.client.App.<init>(App.java:20)
  at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
  at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
  at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
  at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
  at com.google.gwt.dev.shell.ModuleSpace.rebindAndCreate(ModuleSpace.java:465)
  at com.google.gwt.dev.shell.ModuleSpace.onLoad(ModuleSpace.java:375)
  at com.google.gwt.dev.shell.OophmSessionHandler.loadModule(OophmSessionHandler.java:200)
  at com.google.gwt.dev.shell.BrowserChannelServer.processConnection(BrowserChannelServer.java:525)
  at com.google.gwt.dev.shell.BrowserChannelServer.run(BrowserChannelServer.java:363)
  at java.lang.Thread.run(Thread.java:662)
Caused by: java.lang.IncompatibleClassChangeError: Found interface com.google.gwt.core.ext.typeinfo.JClassType, but class was expected
  at org.restlet.rebind.ClientProxyGenerator.generate(ClientProxyGenerator.java:239)
  at com.google.gwt.core.ext.GeneratorExtWrapper.generate(GeneratorExtWrapper.java:48)
  at com.google.gwt.core.ext.GeneratorExtWrapper.generateIncrementally(GeneratorExtWrapper.java:60)
  at com.google.gwt.dev.javac.StandardGeneratorContext.runGeneratorIncrementally(StandardGeneratorContext.java:647)
  at com.google.gwt.dev.cfg.RuleGenerateWith.realize(RuleGenerateWith.java:41)
  at com.google.gwt.dev.shell.StandardRebindOracle$Rebinder.rebind(StandardRebindOracle.java:78)
  at com.google.gwt.dev.shell.StandardRebindOracle.rebind(StandardRebindOracle.java:268)
  at com.google.gwt.dev.shell.ShellModuleSpaceHost.rebind(ShellModuleSpaceHost.java:141)
  at com.google.gwt.dev.shell.ModuleSpace.rebind(ModuleSpace.java:585)
  at com.google.gwt.dev.shell.ModuleSpace.rebindAndCreate(ModuleSpace.java:455)
  at com.google.gwt.dev.shell.GWTBridgeImpl.create(GWTBridgeImpl.java:49)
  at com.google.gwt.core.client.GWT.create(GWT.java:97)
  at com.exposure101.lifelogger.client.App.<init>(App.java:20)
  at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
  at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
  at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
  at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
  at com.google.gwt.dev.shell.ModuleSpace.rebindAndCreate(ModuleSpace.java:465)
  at com.google.gwt.dev.shell.ModuleSpace.onLoad(ModuleSpace.java:375)
  at com.google.gwt.dev.shell.OophmSessionHandler.loadModule(OophmSessionHandler.java:200)
  at com.google.gwt.dev.shell.BrowserChannelServer.processConnection(BrowserChannelServer.java:525)
  at com.google.gwt.dev.shell.BrowserChannelServer.run(BrowserChannelServer.java:363)
  at java.lang.Thread.run(Thread.java:662)

Answer 1

This error generally means you're using a library compiled against GWT 2.1 or earlier with GWT 2.2 or later: GWT 2.2 introduced a binary incompatibility. There's no source-level breaking change though, so recompiling the third-party library against GWT 2.2 is enough to make it work with GWT 2.2 or later.

In other words: try using a more recent version of Restlet; one that has been compiled against a recent version of GWT.