Exception java.lang.ClassFormatError when calling 'mvn exec:java' on a newly cloned seam forge working directory

The following exception is thrown when calling 'mvn exec:java' on a newly checked out workspace.

[INFO] — exec-maven-plugin:1.1.1:java (default-cli) @ forge-distribution —
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 50.373s
[INFO] Finished at: Tue Jul 05 00:31:18 BST 2011
[INFO] Final Memory: 27M/81M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.codehaus.mojo:exec-maven-plugin:1.1.1:java (default-cli) on project forge-distribution: An exception occured while executing the Java class. org.jboss.weld.exceptions.WeldException: by java.lang.ClassFormatError: Illegal class name "org/jboss/weld/environment/se/org$jboss$weld$bean-classpath-ManagedBean-org$jboss$weld$environment$se$ShutdownManager[@javax$enterprise$context$ApplicationScoped()]{}$$_WeldClientProxy" in class file org/jboss/weld/environment/se/org$jboss$weld$bean-classpath-ManagedBean-org$jboss$weld$environment$se$ShutdownManager[@javax$enterprise$context$ApplicationScoped()]{}$$_WeldClientProxy -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException
253:dist ramykamel$ mvn -e exec:java
[INFO] Error stacktraces are turned on.
[INFO] Scanning for projects...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building Forge - Distribution 1.0.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] >>> exec-maven-plugin:1.1.1:java (default-cli) @ forge-distribution >>>
[INFO]
[INFO] — maven-enforcer-plugin:1.0-beta-1:enforce (enforce) @ forge-distribution —
[WARNING] This rule is not compatible with the current version of Maven. The rule is not able to perform any checks.
[INFO]
[INFO] — build-helper-maven-plugin:1.5:maven-version (default) @ forge-distribution —
[INFO]
[INFO] — build-helper-maven-plugin:1.5:parse-version (default) @ forge-distribution —
[INFO]
[INFO] <<< exec-maven-plugin:1.1.1:java (default-cli) @ forge-distribution <<<
[INFO]
[INFO] — exec-maven-plugin:1.1.1:java (default-cli) @ forge-distribution —
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 5.465s
[INFO] Finished at: Tue Jul 05 00:32:13 BST 2011
[INFO] Final Memory: 24M/81M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.codehaus.mojo:exec-maven-plugin:1.1.1:java (default-cli) on project forge-distribution: An exception occured while executing the Java class. org.jboss.weld.exceptions.WeldException: by java.lang.ClassFormatError: Illegal class name "org/jboss/weld/environment/se/org$jboss$weld$bean-classpath-ManagedBean-org$jboss$weld$environment$se$ShutdownManager[@javax$enterprise$context$ApplicationScoped()]{}$$_WeldClientProxy" in class file org/jboss/weld/environment/se/org$jboss$weld$bean-classpath-ManagedBean-org$jboss$weld$environment$se$ShutdownManager[@javax$enterprise$context$ApplicationScoped()]{}$$_WeldClientProxy -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.codehaus.mojo:exec-maven-plugin:1.1.1:java (default-cli) on project forge-distribution: An exception occured while executing the Java class. org.jboss.weld.exceptions.WeldException: by java.lang.ClassFormatError: Illegal class name "org/jboss/weld/environment/se/org$jboss$weld$bean-classpath-ManagedBean-org$jboss$weld$environment$se$ShutdownManager[@javax$enterprise$context$ApplicationScoped()]{}$$_WeldClientProxy" in class file org/jboss/weld/environment/se/org$jboss$weld$bean-classpath-ManagedBean-org$jboss$weld$environment$se$ShutdownManager[@javax$enterprise$context$ApplicationScoped()]{}$$_WeldClientProxy
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:217)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:84)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:59)
at org.apache.maven.lifecycle.internal.LifecycleStarter.singleThreadedBuild(LifecycleStarter.java:183)
at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:161)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:319)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:156)
at org.apache.maven.cli.MavenCli.execute(MavenCli.java:537)
at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:196)
at org.apache.maven.cli.MavenCli.main(MavenCli.java:141)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:290)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:230)
at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:409)
at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:352)
Caused by: org.apache.maven.plugin.MojoExecutionException: An exception occured while executing the Java class. org.jboss.weld.exceptions.WeldException: by java.lang.ClassFormatError: Illegal class name "org/jboss/weld/environment/se/org$jboss$weld$bean-classpath-ManagedBean-org$jboss$weld$environment$se$ShutdownManager[@javax$enterprise$context$ApplicationScoped()]{}$$_WeldClientProxy" in class file org/jboss/weld/environment/se/org$jboss$weld$bean-classpath-ManagedBean-org$jboss$weld$environment$se$ShutdownManager[@javax$enterprise$context$ApplicationScoped()]{}$$_WeldClientProxy
at org.codehaus.mojo.exec.ExecJavaMojo.execute(ExecJavaMojo.java:338)
at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:101)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:209)
... 19 more
Caused by: com.google.common.collect.ComputationException: org.jboss.weld.exceptions.WeldException: by java.lang.ClassFormatError: Illegal class name "org/jboss/weld/environment/se/org$jboss$weld$bean-classpath-ManagedBean-org$jboss$weld$environment$se$ShutdownManager[@javax$enterprise$context$ApplicationScoped()]{}$$_WeldClientProxy" in class file org/jboss/weld/environment/se/org$jboss$weld$bean-classpath-ManagedBean-org$jboss$weld$environment$se$ShutdownManager[@javax$enterprise$context$ApplicationScoped()]{}$$_WeldClientProxy
at com.google.common.collect.ComputingConcurrentHashMap.compute(ComputingConcurrentHashMap.java:218)
at com.google.common.collect.ComputingConcurrentHashMap.apply(ComputingConcurrentHashMap.java:100)
at com.google.common.collect.MapMaker$ComputingMapAdapter.get(MapMaker.java:515)
at org.jboss.weld.bean.proxy.ClientProxyProvider.getClientProxy(ClientProxyProvider.java:113)
at org.jboss.weld.manager.BeanManagerImpl.getReference(BeanManagerImpl.java:681)
at org.jboss.weld.manager.BeanManagerImpl.getReference(BeanManagerImpl.java:728)
at org.jboss.weld.environment.se.Weld.getInstanceByType(Weld.java:161)
at org.jboss.weld.environment.se.Weld.initialize(Weld.java:92)
at org.jboss.forge.shell.Bootstrap$2.run(Bootstrap.java:92)
at java.lang.Thread.run(Thread.java:680)
Caused by: org.jboss.weld.exceptions.WeldException: by java.lang.ClassFormatError: Illegal class name "org/jboss/weld/environment/se/org$jboss$weld$bean-classpath-ManagedBean-org$jboss$weld$environment$se$ShutdownManager[@javax$enterprise$context$ApplicationScoped()]{}$$_WeldClientProxy" in class file org/jboss/weld/environment/se/org$jboss$weld$bean-classpath-ManagedBean-org$jboss$weld$environment$se$ShutdownManager[@javax$enterprise$context$ApplicationScoped()]{}$$_WeldClientProxy
at org.jboss.weld.bean.proxy.ProxyFactory.getProxyClass(ProxyFactory.java:287)
at org.jboss.weld.bean.proxy.ProxyFactory.create(ProxyFactory.java:214)
at org.jboss.weld.bean.proxy.ClientProxyProvider.createClientProxy(ClientProxyProvider.java:97)
at org.jboss.weld.bean.proxy.ClientProxyProvider.access$000(ClientProxyProvider.java:47)
at org.jboss.weld.bean.proxy.ClientProxyProvider$1.apply(ClientProxyProvider.java:61)
at org.jboss.weld.bean.proxy.ClientProxyProvider$1.apply(ClientProxyProvider.java:52)
at com.google.common.collect.ComputingConcurrentHashMap.compute(ComputingConcurrentHashMap.java:206)
... 9 more
Caused by: javassist.CannotCompileException: by java.lang.ClassFormatError: Illegal class name "org/jboss/weld/environment/se/org$jboss$weld$bean-classpath-ManagedBean-org$jboss$weld$environment$se$ShutdownManager[@javax$enterprise$context$ApplicationScoped()]{}$$_WeldClientProxy" in class file org/jboss/weld/environment/se/org$jboss$weld$bean-classpath-ManagedBean-org$jboss$weld$environment$se$ShutdownManager[@javax$enterprise$context$ApplicationScoped()]{}$$_WeldClientProxy
at org.jboss.weld.util.bytecode.ClassFileUtils.toClass(ClassFileUtils.java:117)
at org.jboss.weld.bean.proxy.ProxyFactory.createProxyClass(ProxyFactory.java:402)
at org.jboss.weld.bean.proxy.ProxyFactory.getProxyClass(ProxyFactory.java:283)
... 15 more
Caused by: java.lang.ClassFormatError: Illegal class name "org/jboss/weld/environment/se/org$jboss$weld$bean-classpath-ManagedBean-org$jboss$weld$environment$se$ShutdownManager[@javax$enterprise$context$ApplicationScoped()]{}$$_WeldClientProxy" in class file org/jboss/weld/environment/se/org$jboss$weld$bean-classpath-ManagedBean-org$jboss$weld$environment$se$ShutdownManager[@javax$enterprise$context$ApplicationScoped()]{}$$_WeldClientProxy
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631)
at java.lang.ClassLoader.defineClass(ClassLoader.java:615)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.jboss.weld.util.bytecode.ClassFileUtils.toClass2(ClassFileUtils.java:143)
at org.jboss.weld.util.bytecode.ClassFileUtils.toClass(ClassFileUtils.java:109)
... 17 more