title: GWT webappcreator creating a Maven project: the source attachment does not contain the source for the file URLClassPath.class
body: <p>I have created a Maven2-based GWT application, imported it into Eclipse, and when I Debug As a GWT Web Application, the Eclipse debug session suspends with a FileNotFoundException. It displays a window saying: the source attachment does not contain the source for the file URLClassPath.class.</p>
  
  <p>I have completely wiped out the Eclipse workspace (and .metadata subdirectory), created/imported a blank project and the same thing happens. If I do <strong>Run As</strong> GWT Web Application it works ok (with a couple of warnings). What do I need to tweak to get this working in debug mode?</p>
  
  <h2>Steps to reproduce the problem</h2>
  
  <p><strong>1) Create Application</strong></p>
  
  <p>webAppCreator -noant -maven -XnoEclipse -out MyApp com.example.MyApp</p>
  
  <p><strong>2) Import and change settings</strong></p>
  
  <ul>
  <li><p>The application is imported into the Eclipse workspace, in the settings the "Use Google Web Toolkit" checkbox is ticked.</p></li>
  <li><p>"This project has a WAR directory" is checked. The WAR directory is set to src/main/webapp. The "Launch and deploy from this directory" is unchecked.</p></li>
  </ul>
  
  <p><strong>3) Debug As</strong></p>
  
  <p>Now the debug toolbar button is pressed, choose "GWT Web Application", and select target/www as the WAR directory. You should see the same problem. The call stack in the Debug pane contains the following:</p>
  
  <blockquote>
    <p>MyApp.html [Web Application]<br>
    com.google.gwt.dev.DevMode at
    localhost:51620      Thread [main]
    (Suspended (exception
    FileNotFoundException))<br>
    URLClassPath$JarLoader.getJarFile(URL)
    line: 644<br>
    URLClassPath$JarLoader.access$600(URLClassPath$JarLoader,
    URL) line: 540<br>
    URLClassPath$JarLoader$1.run() line:
    607<br>
    AccessController.doPrivileged(PrivilegedExceptionAction)
    line: not available [native method]<br>
    URLClassPath$JarLoader.ensureOpen()
    line: 599<br>
    URLClassPath$JarLoader.(URL,
    URLStreamHandler,
    HashMap) line: 583<br>
    URLClassPath$JarLoader$3.run() line:
    810<br>
    AccessController.doPrivileged(PrivilegedExceptionAction)
    line: not available [native method]<br>
    URLClassPath$JarLoader.getResource(String,
    boolean, Set) line: 806<br>
    URLClassPath$JarLoader.getResource(String,
    boolean) line: 765<br>
    URLClassPath.getResource(String,
    boolean) line: 169<br>
    URLClassLoader$1.run() line: 194<br>
    AccessController.doPrivileged(PrivilegedExceptionAction,
    AccessControlContext) line: not
    available [native method]<br>
    Launcher$AppClassLoader(URLClassLoader).findClass(String)
    line: 190<br>
    Launcher$AppClassLoader(ClassLoader).loadClass(String,
    boolean) line: 307<br>
    Launcher$AppClassLoader.loadClass(String,
    boolean) line: 301<br>
    Launcher$AppClassLoader(ClassLoader).loadClass(String)
    line: 248   C:\Program
    Files\Java\jdk1.6.0_21\bin\javaw.exe
    (28 Nov 2010 15:28:32)</p>
  </blockquote>
  
  <h2>Versions and plugins</h2>
  
  <p>GWT: 2.1.</p>
  
  <p>Eclipse: Helios (3.6).</p>
  
  <p>Maven: 2.2.1.</p>
  
  <p>JRE/JDK: JDK 1.6.0.21.</p>
  
  <p>Google Plugin for Eclipse 3.6 version 1.4.0.v201010280102.</p>
  
  <p>Maven Integration for Eclipse (m2eclipse) version 0.10.2.20100623-1649 (this has been configured to point to Maven 2.2.1 environment and NOT to use the embedded Maven3 "instance").</p>