Clientgen Ant Task fails with "ClassNotFoundException: [B"

Question

I'm trying to run the clientgen Ant Task and I get weird error: a java.lang.ClassNotFoundException: [B
Maybe Im missing something on my classpath but the cryptic message is preventing me from determining what exactly.
Do you guys have any ideas?
Extract build.xml:
<clientgen ear="${expl.dir}"
serviceName="SwiftcomInterfaceService"
packageName="com.jnj.gtsc.swiftcom2.business.swiftcom.business.webservice.client"
useServerTypes="True"
     warName="InterfaceWS"
     savewsdl="true"
clientJar="${dist.dir}/swiftcomWS_client.jar" >
<classpath refid="wsclient-classpath" />
</clientgen>
wsclient-classpath:
contains only Weblogic 8.1 sp 6 webservice.jar and webserviceclient.jar
Stacktrace:
[clientgen] Generating client jar for swiftcom2Ear(SwiftcomInterfaceService) ...
[clientgen] weblogic.webservice.server.ConfigException: unable to load class:[ java.lang.ClassNotFoundException: [B
[clientgen] at weblogic.webservice.server.WebServiceFactory.loadClass(WebServiceFactory.java:1295)
[clientgen] at weblogic.webservice.dd.MethodDescriptor.<init>(MethodDescriptor.java:45)
[clientgen] at weblogic.webservice.server.WebServiceFactory.registerOperation(WebServiceFactory.java:813)
[clientgen] at weblogic.webservice.server.WebServiceFactory.initOperations(WebServiceFactory.java:633)
[clientgen] at weblogic.webservice.server.WebServiceFactory.createFromMBean(WebServiceFactory.java:220)
[clientgen] at weblogic.webservice.tools.build.internal.WSDLGenImpl.getWebServiceRuntime(WSDLGenImpl.java:240)
[clientgen] at weblogic.webservice.tools.build.internal.WSDLGenImpl.run(WSDLGenImpl.java:135)
[clientgen] at weblogic.webservice.tools.build.internal.ClientGenImpl.doClientGenFromEAR(ClientGenImpl.java:454)
[clientgen] at weblogic.webservice.tools.build.internal.ClientGenImpl.run(ClientGenImpl.java:348)
[clientgen] at weblogic.ant.taskdefs.webservices.clientgen.ClientGenTask.doClientGen(ClientGenTask.java:352)
[clientgen] at weblogic.ant.taskdefs.webservices.clientgen.ClientGenTask.execute(ClientGenTask.java:208)
[clientgen] at org.apache.tools.ant.Task.perform(Task.java:341)
[clientgen] at org.apache.tools.ant.Target.execute(Target.java:309)
[clientgen] at org.apache.tools.ant.Target.performTasks(Target.java:336)
[clientgen] at org.apache.tools.ant.Project.executeTarget(Project.java:1339)
[clientgen] at org.apache.tools.ant.taskdefs.Ant.execute(Ant.java:397)
[clientgen] at org.apache.tools.ant.taskdefs.CallTarget.execute(CallTarget.java:143)
[clientgen] at org.apache.tools.ant.Task.perform(Task.java:341)
[clientgen] at org.apache.tools.ant.Target.execute(Target.java:309)
[clientgen] at org.apache.tools.ant.Target.performTasks(Target.java:336)
[clientgen] at org.apache.tools.ant.Project.executeTarget(Project.java:1339)
[clientgen] at org.apache.tools.ant.taskdefs.Ant.execute(Ant.java:397)
[clientgen] at org.apache.tools.ant.taskdefs.CallTarget.execute(CallTarget.java:143)
[clientgen] at org.apache.tools.ant.Task.perform(Task.java:341)
[clientgen] at org.apache.tools.ant.Target.execute(Target.java:309)
[clientgen] at org.apache.tools.ant.Target.performTasks(Target.java:336)
[clientgen] at org.apache.tools.ant.Project.executeTarget(Project.java:1339)
[clientgen] at org.apache.tools.ant.Project.executeTargets(Project.java:1255)
[clientgen] at org.apache.tools.ant.Main.runBuild(Main.java:609)
[clientgen] at org.apache.tools.ant.Main.start(Main.java:196)
[clientgen] at org.apache.tools.ant.Main.main(Main.java:235)

Answer 1

I found out what the problem was: wrong version of JDK.
I was calling my Ant script from Maven and it was executing the Ant script with the Java 6. Once I set the JAVA_HOME in the Maven call to a 1.4 JDK it worked.
<plugin>
                    <groupId>org.codehaus.mojo</groupId>
                    <artifactId>exec-maven-plugin</artifactId>
                    <version>1.2</version>
                    <executions>
                         <execution>
                              <id>run-ant</id>
                              <phase>package</phase>
                              <goals>
                                   <goal>exec</goal>
                              </goals>
                         </execution>
                    </executions>
                    <configuration>
                         <executable>cmd.exe</executable>
                         <commandlineArgs>/X /C ${env.ANT_HOME}/bin/ant build-all</commandlineArgs>
                         <environmentVariables>
                              <JAVA_HOME>${jdk-1.4}</JAVA_HOME>
                         </environmentVariables>
                    </configuration>
               </plugin>