Setting XPage fileDownload via JavaBean

I like to set an xp:fileDownload via a JavaBean. The JavaBean returns a FileRowData object. But the XPage returns error
"java.lang.ClassCastException: com.ibm.xsp.model.domino.wrapped.DominoDocument$AttachmentValueHolder incompatible with [Lcom.ibm.xsp.model.FileRowData;
"

According to
http://public.dhe.ibm.com/software/dw/lotus/Domino-Designer/JavaDocs/XPagesExtAPI/8.5.2/com/ibm/xsp/model/domino/wrapped/DominoDocument.AttachmentValueHolder.html
AttachmentValueHolder implements interface FileRowData. But it can not casted to FileRowData?

The code to set the value of xp:fileDownload:
DominoDocument ddCurrent = new DominoDocument();
ddCurrent.setDocument(ndCurrent);
return ddCurrent.getAttachmentList(IdeaConstants.ITEM_ATTACHMENTS).get(0);

ndCurrent ist my (Notes-) Document.

Questions:

  1. Why do I get a ClassCastException?
  2. How to set a list/array of attachments to xp:fileDownload?

Exception
com.ibm.xsp.model.domino.wrapped.DominoDocument$AttachmentValueHolder incompatible with [Lcom.ibm.xsp.model.FileRowData;

► ▼ Stack Trace

java.lang.ClassCastException: com.ibm.xsp.model.domino.wrapped.DominoDocument$AttachmentValueHolder incompatible with [Lcom.ibm.xsp.model.FileRowData;
com.ibm.xsp.component.UIFileDownload.getFileRowData(UIFileDownload.java:1365)
com.ibm.xsp.component.UIFileDownload.getEffectiveSizeValue(UIFileDownload.java:1398)
com.ibm.xsp.component.UIFileDownload$InternalSizeValue.getValue(UIFileDownload.java:1380)
javax.faces.component.UIOutput.getValue(UIOutput.java:159)
com.ibm.xsp.util.FacesUtil.convertValue(FacesUtil.java:1073)
com.ibm.xsp.renderkit.html_basic.OutputTextRenderer.encodeEnd(OutputTextRenderer.java:91)
com.ibm.xsp.renderkit.ReadOnlyAdapterRenderer.encodeEnd(ReadOnlyAdapterRenderer.java:153)
javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:1005)
com.ibm.xsp.util.FacesUtil.renderComponent(FacesUtil.java:809)
com.ibm.xsp.util.FacesUtil.renderChildren(FacesUtil.java:824)
com.ibm.xsp.renderkit.html_extended.FileDownloadRenderer.encodeChildren(FileDownloadRenderer.java:139)
com.ibm.xsp.renderkit.ReadOnlyAdapterRenderer.encodeChildren(ReadOnlyAdapterRenderer.java:135)
javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:979)
com.ibm.xsp.util.FacesUtil.renderComponent(FacesUtil.java:795)
com.ibm.xsp.util.FacesUtil.renderChildren(FacesUtil.java:824)
com.ibm.xsp.renderkit.html_extended.HtmlBasicRenderer.encodeChildren(HtmlBasicRenderer.java:159)
com.ibm.xsp.renderkit.ReadOnlyAdapterRenderer.encodeChildren(ReadOnlyAdapterRenderer.java:135)
javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:979)
com.ibm.xsp.util.FacesUtil.renderComponent(FacesUtil.java:795)
com.ibm.xsp.util.FacesUtil.renderChildren(FacesUtil.java:824)
com.ibm.xsp.renderkit.html_extended.HtmlBasicRenderer.encodeChildren(HtmlBasicRenderer.java:159)
com.ibm.xsp.renderkit.ReadOnlyAdapterRenderer.encodeChildren(ReadOnlyAdapterRenderer.java:135)
javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:979)
com.ibm.xsp.util.FacesUtil.renderComponent(FacesUtil.java:795)
com.ibm.xsp.util.FacesUtil.renderChildren(FacesUtil.java:824)
com.ibm.xsp.renderkit.html_extended.HtmlBasicRenderer.encodeChildren(HtmlBasicRenderer.java:159)
com.ibm.xsp.renderkit.ReadOnlyAdapterRenderer.encodeChildren(ReadOnlyAdapterRenderer.java:135)
javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:979)
com.ibm.xsp.util.FacesUtil.renderComponent(FacesUtil.java:795)
com.ibm.xsp.util.FacesUtil.renderComponent(FacesUtil.java:804)
com.ibm.xsp.util.FacesUtil.renderComponent(FacesUtil.java:804)
com.ibm.xsp.util.FacesUtil.renderComponent(FacesUtil.java:804)
com.ibm.xsp.util.FacesUtil.renderComponent(FacesUtil.java:804)
com.ibm.xsp.util.FacesUtil.renderComponent(FacesUtil.java:804)
com.ibm.xsp.extlib.renderkit.html_extended.layout.AbstractApplicationLayoutRenderer.renderChildren(AbstractApplicationLayoutRenderer.java:645)
com.ibm.xsp.extlib.renderkit.html_extended.layout.AbstractApplicationLayoutRenderer.writeContentColumn(AbstractApplicationLayoutRenderer.java:507)
com.ibm.xsp.extlib.renderkit.html_extended.layout.AbstractApplicationLayoutRenderer.writeMainContent(AbstractApplicationLayoutRenderer.java:452)
com.ibm.xsp.extlib.renderkit.html_extended.layout.AbstractApplicationLayoutRenderer.writeMainFrame(AbstractApplicationLayoutRenderer.java:110)
com.ibm.xsp.extlib.renderkit.html_extended.layout.AbstractApplicationLayoutRenderer.encodeBegin(AbstractApplicationLayoutRenderer.java:611)
com.ibm.xsp.renderkit.ReadOnlyAdapterRenderer.encodeBegin(ReadOnlyAdapterRenderer.java:119)
javax.faces.component.UIComponentBase.encodeBegin(UIComponentBase.java:956)
com.ibm.xsp.extlib.component.layout.UIApplicationLayout.encodeBegin(UIApplicationLayout.java:200)
com.ibm.xsp.util.FacesUtil.renderComponent(FacesUtil.java:793)
com.ibm.xsp.util.FacesUtil.renderComponent(FacesUtil.java:804)
com.ibm.xsp.util.FacesUtil.renderComponent(FacesUtil.java:804)
com.ibm.xsp.util.FacesUtil.renderComponent(FacesUtil.java:804)
com.ibm.xsp.util.FacesUtil.renderComponent(FacesUtil.java:804)
com.ibm.xsp.component.UIViewRootEx._renderView(UIViewRootEx.java:1272)
com.ibm.xsp.component.UIViewRootEx.renderView(UIViewRootEx.java:1210)
com.ibm.xsp.application.ViewHandlerExImpl.doRender(ViewHandlerExImpl.java:635)
com.ibm.xsp.application.ViewHandlerExImpl._renderView(ViewHandlerExImpl.java:320)
com.ibm.xsp.application.ViewHandlerExImpl.renderView(ViewHandlerExImpl.java:355)
com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:103)
com.sun.faces.lifecycle.LifecycleImpl.phase(LifecycleImpl.java:210)
com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:120)
com.ibm.xsp.controller.FacesControllerImpl.render(FacesControllerImpl.java:264)
com.ibm.xsp.webapp.FacesServlet.serviceView(FacesServlet.java:219)
com.ibm.xsp.webapp.FacesServletEx.serviceView(FacesServletEx.java:193)
com.ibm.xsp.webapp.FacesServlet.service(FacesServlet.java:154)
com.ibm.xsp.webapp.FacesServletEx.service(FacesServletEx.java:137)
com.ibm.xsp.webapp.DesignerFacesServlet.service(DesignerFacesServlet.java:86)
com.ibm.designer.runtime.domino.adapter.ComponentModule.invokeServlet(ComponentModule.java:538)
com.ibm.domino.xsp.module.nsf.NSFComponentModule.invokeServlet(NSFComponentModule.java:1140)
com.ibm.designer.runtime.domino.adapter.ComponentModule$AdapterInvoker.invokeServlet(ComponentModule.java:803)
com.ibm.designer.runtime.domino.adapter.ComponentModule$ServletInvoker.doService(ComponentModule.java:758)
com.ibm.designer.runtime.domino.adapter.ComponentModule.doService(ComponentModule.java:527)
com.ibm.domino.xsp.module.nsf.NSFComponentModule.doService(NSFComponentModule.java:1124)
com.ibm.domino.xsp.module.nsf.NSFService.doServiceInternal(NSFService.java:513)
com.ibm.domino.xsp.module.nsf.NSFService.doService(NSFService.java:342)
com.ibm.designer.runtime.domino.adapter.LCDEnvironment.doService(LCDEnvironment.java:304)
com.ibm.designer.runtime.domino.adapter.LCDEnvironment.service(LCDEnvironment.java:261)
com.ibm.domino.xsp.bridge.http.engine.XspCmdManager.service(XspCmdManager.java:291)