Problem with Findbugs and checkstyle

I have a big problem. I wanted to connect two plugins together, but including 
checkstyle into my plugins pom i get an error:

[INFO] ------------------------------------------------------------------------
[ERROR] FATAL ERROR
[INFO] ------------------------------------------------------------------------
[INFO] Cannot inherit from final class
[INFO] ------------------------------------------------------------------------
[INFO] Trace
java.lang.VerifyError: Cannot inherit from final class
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:620)
        at 
java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:260)
        at java.net.URLClassLoader.access$100(URLClassLoader.java:56)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
        at 
org.codehaus.classworlds.RealmClassLoader.loadClassDirect(RealmClassLoader.java:195)
        at 
org.codehaus.classworlds.DefaultClassRealm.loadClass(DefaultClassRealm.java:255)
        at 
org.codehaus.classworlds.RealmClassLoader.loadClass(RealmClassLoader.java:214)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
        at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)
        at java.lang.Class.getDeclaredMethods0(Native Method)
        at java.lang.Class.privateGetDeclaredMethods(Class.java:2365)
        at java.lang.Class.getDeclaredMethod(Class.java:1907)
        at edu.umd.cs.findbugs.DetectorFactory.<init>(DetectorFactory.java:80)
        at edu.umd.cs.findbugs.PluginLoader.init(PluginLoader.java:198)
        at edu.umd.cs.findbugs.PluginLoader.<init>(PluginLoader.java:87)
        at 
edu.umd.cs.findbugs.DetectorFactoryCollection.loadPlugins(DetectorFactoryCollection.java:200)
        at 
edu.umd.cs.findbugs.DetectorFactoryCollection.<init>(DetectorFactoryCollection.java:55)
        at 
edu.umd.cs.findbugs.DetectorFactoryCollection.instance(DetectorFactoryCollection.java:76)
        at 
edu.umd.cs.findbugs.config.UserPreferences.enableAllDetectors(UserPreferences.java:314)
        at 
de.sdm.maven.dashboard.DashboardMojo.initialiseFindBugs(DashboardMojo.java:213)
        at 
de.sdm.maven.dashboard.DashboardMojo.executeReport(DashboardMojo.java:263)
        at 
org.apache.maven.reporting.AbstractMavenReport.generate(AbstractMavenReport.java:98)
        at 
org.apache.maven.plugins.site.SiteMojo.generateReportsPages(SiteMojo.java:802)
        at org.apache.maven.plugins.site.SiteMojo.execute(SiteMojo.java:301)
        at 
org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPluginManager.java:412)
        at 
org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:534)
        at 
org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalWithLifecycle(DefaultLifecycleExecutor.java:475)
        at 
org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(DefaultLifecycleExecutor.java:454)
        at 
org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHandleFailures(DefaultLifecycleExecutor.java:306)
        at 
org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegments(DefaultLifecycleExecutor.java:273)
        at 
org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:140)
        at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:322)
        at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:115)
        at org.apache.maven.cli.MavenCli.main(MavenCli.java:256)
        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:585)
        at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315)
        at org.codehaus.classworlds.Launcher.launch(Launcher.java:255)
        at org.codehaus.classworlds.Launcher.mainWithExitCode(Launcher.java:430)
        at org.codehaus.classworlds.Launcher.main(Launcher.java:375)
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 10 seconds
[INFO] Finished at: Tue Aug 08 16:39:12 CEST 2006
[INFO] Final Memory: 8M/15M
[INFO] ------------------------------------------------------------------------


i tried to modify the checkstyle pom, exclude the inner classes, but all of 
them all necessary (like commons-beanutils). 
Could someone check it ?
Once again:
include checkstyle 4.1 into your maven-findbugs-plugin pom and you will get the 
promlem described above.