after a while without clicking on the web app (5 minutes maybe) if we start by clicking on the jsf tree, anexception is thrown, and the only thing we can do is log off

I was logged as administrator, and reproduced it many times :

java.lang.UnsupportedOperationException: Cannot load data models for client defined models
org.nuxeo.ecm.core.api.impl.DocumentModelImpl.getClient(DocumentModelImpl.java:348)
org.nuxeo.ecm.core.api.impl.DocumentModelImpl.loadDataModel(DocumentModelImpl.java:364)
org.nuxeo.ecm.core.api.impl.DocumentModelImpl.getDataModel(DocumentModelImpl.java:386)
org.nuxeo.ecm.core.api.impl.DocumentModelImpl.getProperty(DocumentModelImpl.java:494)
org.nuxeo.ecm.platform.ui.web.tag.fn.DocumentModelFunctions.iconExpandedPath(DocumentModelFunctions.java:82)
sun.reflect.GeneratedMethodAccessor501.invoke(Unknown Source)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
java.lang.reflect.Method.invoke(Method.java:585)
com.sun.el.parser.AstFunction.getValue(AstFunction.java:114)
com.sun.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:192)
com.sun.facelets.el.TagValueExpression.getValue(TagValueExpression.java:71)
javax.faces.component.UIGraphic.getValue(UIGraphic.java:137)
com.sun.faces.renderkit.html_basic.ImageRenderer.src(ImageRenderer.java:139)
com.sun.faces.renderkit.html_basic.ImageRenderer.encodeEnd(ImageRenderer.java:112)
javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:833)
com.sun.faces.renderkit.html_basic.OutputLinkRenderer.encodeChildren(OutputLinkRenderer.java:152)
javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:809)
com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeRecursive(HtmlBasicRenderer.java:271)
com.sun.faces.renderkit.html_basic.GroupRenderer.encodeChildren(GroupRenderer.java:117)
javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:809)
org.apache.myfaces.shared_tomahawk.renderkit.RendererUtils.renderChild(RendererUtils.java:414)
org.apache.myfaces.custom.tree2.HtmlTreeRenderer.encodeCurrentNode(HtmlTreeRenderer.java:364)
org.nuxeo.ecm.platform.ui.web.tree.HtmlLazyTreeRenderer.encodeTree(HtmlLazyTreeRenderer.java:95)
org.nuxeo.ecm.platform.ui.web.tree.HtmlLazyTreeRenderer.encodeChildren(HtmlLazyTreeRenderer.java:61)
javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:809)
com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeRecursive(HtmlBasicRenderer.java:271)
com.sun.faces.renderkit.html_basic.GroupRenderer.encodeChildren(GroupRenderer.java:117)
javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:809)
org.ajax4jsf.framework.renderer.RendererBase.renderChild(RendererBase.java:252)
org.ajax4jsf.framework.renderer.RendererBase.renderChildren(RendererBase.java:232)
org.ajax4jsf.framework.renderer.RendererBase.renderChild(RendererBase.java:254)
org.ajax4jsf.framework.renderer.RendererBase.renderChildren(RendererBase.java:232)
org.ajax4jsf.framework.renderer.AjaxContainerRenderer.encodeChildren(AjaxContainerRenderer.java:100)
javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:809)
org.ajax4jsf.ajax.UIAjaxRegion.encodeChildren(UIAjaxRegion.java:119)
javax.faces.component.UIComponent.encodeAll(UIComponent.java:886)
javax.faces.component.UIComponent.encodeAll(UIComponent.java:892)
com.sun.facelets.FaceletViewHandler.renderView(FaceletViewHandler.java:578)
org.apache.myfaces.trinidadinternal.application.ViewHandlerImpl.renderView(ViewHandlerImpl.java:181)
org.ajax4jsf.framework.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:108)
org.ajax4jsf.framework.ajax.AjaxViewHandler.renderView(AjaxViewHandler.java:229)
com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:106)
com.sun.faces.lifecycle.LifecycleImpl.phase(LifecycleImpl.java:251)
com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:144)
javax.faces.webapp.FacesServlet.service(FacesServlet.java:245)
org.apache.myfaces.webapp.filter.ExtensionsFilter.doFilter(ExtensionsFilter.java:100)
org.apache.myfaces.webapp.filter.ExtensionsFilter.doFilter(ExtensionsFilter.java:147)
org.apache.myfaces.trinidadinternal.webapp.TrinidadFilterImpl._invokeDoFilter(TrinidadFilterImpl.java:209)
org.apache.myfaces.trinidadinternal.webapp.TrinidadFilterImpl._doFilterImpl(TrinidadFilterImpl.java:166)
org.apache.myfaces.trinidadinternal.webapp.TrinidadFilterImpl.doFilter(TrinidadFilterImpl.java:139)
org.apache.myfaces.trinidad.webapp.TrinidadFilter.doFilter(TrinidadFilter.java:92)
org.ajax4jsf.framework.ajax.xmlfilter.BaseXMLFilter.doXmlFilter(BaseXMLFilter.java:96)
org.ajax4jsf.framework.ajax.xmlfilter.BaseFilter.doFilter(BaseFilter.java:220)
org.nuxeo.ecm.platform.ui.web.rest.FancyURLFilter.doFilter(FancyURLFilter.java:67)
org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)