Running over ubuntu

Howdy,

When I tried to run GWT quick start tutorial I got this error message!

How can I fix this issue?

• I already installed GWT Developer plugin for Firefox 1.23
• I installed eclipse from ubuntu 13.04 repository (version 3.8.1)
• I already GWT from ubuntu 13.04 repository (version 2.4.0)

02:00:37.373 [ERROR] [hellostupid] Exception initializing module    java.lang.NullPointerException: null      at com.google.gwt.dev.javac.JsniChecker.getSuppressedWarnings(JsniChecker.java:565)      at com.google.gwt.dev.javac.JsniChecker$JsniDeclChecker.visit(JsniChecker.java:135)      at org.eclipse.jdt.internal.compiler.ast.TypeDeclaration.traverse(TypeDeclaration.java:1233)      at org.eclipse.jdt.internal.compiler.ast.CompilationUnitDeclaration.traverse(CompilationUnitDeclaration.java:679)      at com.google.gwt.dev.javac.JsniChecker.check(JsniChecker.java:615)      at com.google.gwt.dev.javac.JsniChecker.check(JsniChecker.java:559)      at com.google.gwt.dev.javac.CompilationStateBuilder$CompileMoreLater$UnitProcessorImpl.process(CompilationStateBuilder.java:83)      at com.google.gwt.dev.javac.JdtCompiler$CompilerImpl.process(JdtCompiler.java:251)      at org.eclipse.jdt.internal.compiler.Compiler.compile(Compiler.java:464)      at com.google.gwt.dev.javac.JdtCompiler.doCompile(JdtCompiler.java:710)      at com.google.gwt.dev.javac.CompilationStateBuilder$CompileMoreLater.compile(CompilationStateBuilder.java:235)      at com.google.gwt.dev.javac.CompilationStateBuilder.doBuildFrom(CompilationStateBuilder.java:447)      at com.google.gwt.dev.javac.CompilationStateBuilder.buildFrom(CompilationStateBuilder.java:370)      at com.google.gwt.dev.cfg.ModuleDef.getCompilationState(ModuleDef.java:360)      at com.google.gwt.dev.DevModeBase$UiBrowserWidgetHostImpl.createModuleSpaceHost(DevModeBase.java:110)      at com.google.gwt.dev.shell.OophmSessionHandler.loadModule(OophmSessionHandler.java:197)      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:724)      
The project was not built since its build path is incomplete. Cannot find the class file for javax.servlet.http.HttpServletResponse. Fix the build path then try building this project	HelloStupid		Unknown	Java Problem  The type javax.servlet.http.HttpServletResponse cannot be resolved. It is indirectly referenced from required .class files	GreetingServiceImpl.java	/HelloStupid/src/com/example/hello/server	line 1	Java Problem  
  

--   Best Regards,  Muhammad Bashir Al-Noimi