Filter stream Generic XML Output Failure

<stackTrace>           <trace>com.thoughtworks.xstream.core.TreeMarshaller.convert(TreeMarshaller.java:63)</trace>            <trace>com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:58)</trace>           <trace>com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:43)</trace>           <trace>com.thoughtworks.xstream.converters.collections.AbstractCollectionConverter.writeItem(AbstractCollectionConverter.java:64)</trace>          <trace>com.thoughtworks.xstream.converters.collections.MapConverter.marshal(MapConverter.java:79)</trace>          <trace>com.thoughtworks.xstream.core.TreeMarshaller.convert(TreeMarshaller.java:70)</trace>           <trace>com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:58)</trace>            <trace>com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.marshallField(AbstractReflectionConverter.java:256)</trace>           <trace>com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter$2.writeField(AbstractReflectionConverter.java:232)</trace>           <trace>com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter$2.&lt;init&gt;(AbstractReflectionConverter.java:195)</trace>           <trace>com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.doMarshal(AbstractReflectionConverter.java:141)</trace>            <trace>com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.marshal(AbstractReflectionConverter.java:89)</trace>          <trace>com.thoughtworks.xstream.core.TreeMarshaller.convert(TreeMarshaller.java:70)</trace>            <trace>com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:58)</trace>            <trace>com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.marshallField(AbstractReflectionConverter.java:256)</trace>           <trace>com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter$2.writeField(AbstractReflectionConverter.java:232)</trace>            <trace>com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter$2.&lt;init&gt;(AbstractReflectionConverter.java:195)</trace>            <trace>com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.doMarshal(AbstractReflectionConverter.java:141)</trace>            <trace>com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.marshal(AbstractReflectionConverter.java:89)</trace>            <trace>com.thoughtworks.xstream.core.TreeMarshaller.convert(TreeMarshaller.java:70)</trace>            <trace>com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:58)</trace>            <trace>com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.marshallField(AbstractReflectionConverter.java:256)</trace>            <trace>com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter$2.writeField(AbstractReflectionConverter.java:232)</trace>            <trace>com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter$2.&lt;init&gt;(AbstractReflectionConverter.java:195)</trace>            <trace>com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.doMarshal(AbstractReflectionConverter.java:141)</trace>           <trace>com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.marshal(AbstractReflectionConverter.java:89)</trace>            <trace>com.thoughtworks.xstream.core.TreeMarshaller.convert(TreeMarshaller.java:70)</trace>            <trace>com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:58)</trace>            <trace>com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:43)</trace>            <trace>org.xwiki.filter.xml.internal.parameter.XMLTreeMarshaller.start(XMLTreeMarshaller.java:61)</trace>           <trace>com.thoughtworks.xstream.core.AbstractTreeMarshallingStrategy.marshal(AbstractTreeMarshallingStrategy.java:37)</trace>
<trace>com.thoughtworks.xstream.XStream.marshal(XStream.java:1043)</trace>            <trace>org.xwiki.filter.xml.internal.parameter.XStreamParameterManager.serialize(XStreamParameterManager.java:126)</trace>            <trace>org.xwiki.filter.xml.internal.serializer.DefaultXMLSerializer.writeParameters(DefaultXMLSerializer.java:327)</trace>            <trace>org.xwiki.filter.xml.internal.serializer.DefaultXMLSerializer.onEvent(DefaultXMLSerializer.java:245)</trace>            <trace>org.xwiki.filter.xml.internal.serializer.DefaultXMLSerializer.invoke(DefaultXMLSerializer.java:352)</trace>
<trace>com.sun.proxy.$Proxy154.onWikiObjectProperty(Unknown Source)</trace>            <trace>org.xwiki.filter.instance.internal.input.BasePropertyEventGenerator.write(BasePropertyEventGenerator.java:47)</trace>    <trace>org.xwiki.filter.instance.internal.input.BasePropertyEventGenerator.write(BasePropertyEventGenerator.java:36)</trace>            <trace>org.xwiki.filter.instance.internal.input.AbstractBeanEntityEventGenerator.write(AbstractBeanEntityEventGenerator.java:114)</trace>            <trace>org.xwiki.filter.instance.internal.input.BaseObjectEventGenerator.write(BaseObjectEventGenerator.java:96)</trace>        <trace>org.xwiki.filter.instance.internal.input.XWikiDocumentLocaleEventGenerator.writeRevision(XWikiDocumentLocaleEventGenerator.java:210)</trace>           <trace>org.xwiki.filter.instance.internal.input.XWikiDocumentLocaleEventGenerator.write(XWikiDocumentLocaleEventGenerator.java:109)</trace>           <trace>org.xwiki.filter.instance.internal.input.XWikiDocumentLocaleEventGenerator.write(XWikiDocumentLocaleEventGenerator.java:55)</trace>           <trace>org.xwiki.filter.instance.internal.input.AbstractBeanEntityEventGenerator.write(AbstractBeanEntityEventGenerator.java:114)</trace>            <trace>org.xwiki.filter.instance.input.AbstractEntityEventGenerator.write(AbstractEntityEventGenerator.java:77)</trace>           <trace>org.xwiki.filter.instance.internal.input.DocumentInstanceInputEventGenerator.beginWikiDocument(DocumentInstanceInputEventGenerator.java:107)</trace>           <trace>org.xwiki.filter.instance.internal.input.InstanceInputFilterStream.writeDocument(InstanceInputFilterStream.java:229)</trace>            <trace>org.xwiki.filter.instance.internal.input.InstanceInputFilterStream.writeSpace(InstanceInputFilterStream.java:195)</trace>            <trace>org.xwiki.filter.instance.internal.input.InstanceInputFilterStream.writeWiki(InstanceInputFilterStream.java:161)</trace>           <trace>org.xwiki.filter.instance.internal.input.InstanceInputFilterStream.read(InstanceInputFilterStream.java:130)</trace>          <trace>org.xwiki.filter.instance.internal.input.InstanceInputFilterStream.read(InstanceInputFilterStream.java:54)</trace>            <trace>org.xwiki.filter.input.AbstractBeanInputFilterStream.read(AbstractBeanInputFilterStream.java:80)</trace>           <trace>org.xwiki.filter.internal.job.FilterStreamConverterJob.runInternal(FilterStreamConverterJob.java:98)</trace>
<trace>org.xwiki.job.AbstractJob.runInContext(AbstractJob.java:205)</trace>
<trace>org.xwiki.job.AbstractJob.run(AbstractJob.java:188)</trace>            <trace>org.xwiki.filter.script.internal.ScriptFilterStreamConverterJob.run(ScriptFilterStreamConverterJob.java:75)</trace>        <trace>java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)</trace>            <trace>java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)</trace>
<trace>java.lang.Thread.run(Thread.java:744)</trace>