StringIndexOutOfBoundsException while executing eclipse:rad for a RAD7 EAR project

When executing the eclipse:rad command for my EAR project, i get this stack :

[INFO] String index out of range: 2
[INFO] ------------------------------------------------------------------------
[INFO] Trace
java.lang.StringIndexOutOfBoundsException: String index out of range: 2
at java.lang.String.charAt(String.java:558)
at org.apache.maven.plugin.eclipse.writers.rad.RadJ2EEWriter.writeModuleTypeFacetCore(RadJ2EEWriter.java:120)
at org.apache.maven.plugin.eclipse.writers.rad.RadJ2EEWriter.write(RadJ2EEWriter.java:88)
at org.apache.maven.plugin.eclipse.RadPlugin.writeConfigurationExtras(RadPlugin.java:140)
at org.apache.maven.plugin.eclipse.EclipsePlugin.writeConfiguration(EclipsePlugin.java:1093)
at org.apache.maven.plugin.ide.AbstractIdeSupportMojo.execute(AbstractIdeSupportMojo.java:511)
at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPluginManager.java:490)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:694)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeStandaloneGoal(DefaultLifecycleExecutor.java:569)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(DefaultLifecycleExecutor.java:539)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHandleFailures(DefaultLifecycleExecutor.java:387)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegments(DefaultLifecycleExecutor.java:348)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:180)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:328)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:138)
at org.apache.maven.cli.MavenCli.main(MavenCli.java:362)
at org.apache.maven.cli.compat.CompatibleMain.main(CompatibleMain.java:60)
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:592)
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)

When i looked at the source code, it looks for a jeeversion, i've tried to set it in my configuration without any improvment...

Here is my plugin configuration :
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-eclipse-plugin</artifactId>
<version>2.8</version>
<configuration>
<wtpversion>1.5</wtpversion>
<additionalConfig>
<file>
<name>.checkstyle</name>
<location>../antenne-conf/src/main/config/checkstyle/checkstyle-config.xml</location>
</file>
<file>
<name>suppressionFilter.xml</name>
<location>../antenne-conf/src/main/config/checkstyle/suppressionFilter.xml</location>
</file>
</additionalConfig>
<classpathContainers>
<classpathContainer>org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/WebSphere v6.1 JRE</classpathContainer>
<classpathContainer>org.eclipse.jst.server.core.container/com.ibm.ws.ast.st.runtime.runtimeTarget.v61/was.base.v61</classpathContainer>
<classpathContainer>org.eclipse.jst.j2ee.internal.module.container</classpathContainer>
</classpathContainers>

<additionalBuildcommands>
<buildcommand>org.eclipse.wst.common.modulecore.ComponentStructuralBuilder</buildcommand>
<buildcommand>com.ibm.etools.common.migration.MigrationBuilder</buildcommand>
<buildcommand>org.eclipse.jdt.core.javabuilder</buildcommand>
<buildcommand>org.eclipse.wst.validation.validationbuilder</buildcommand>
<buildcommand>org.eclipse.wst.common.project.facet.core.builder</buildcommand>
<buildCommand>com.atlassw.tools.eclipse.checkstyle.CheckstyleBuilder</buildCommand>
</additionalBuildcommands>

<additionalProjectnatures>
<projectnature>org.eclipse.wst.common.modulecore.ModuleCoreNature</projectnature>
<projectnature>org.eclipse.wst.common.project.facet.core.nature</projectnature>
<projectnature>com.atlassw.tools.eclipse.checkstyle.CheckstyleNature</projectnature>
</additionalProjectnatures>

<additionalProjectFacets>
<com.ibm.websphere.extended.ejb>6.1</com.ibm.websphere.extended.ejb>
<jst.ear>1.4</jst.ear>
</additionalProjectFacets>
</configuration>
</plugin>

Thanks in advance
Regards
Matthieu