Add client behavior dynamically with var components - jsf

Question

I'm trying to listen event from components contained in DynaForm of primefaces-extensions, so developer can do dynamically do some custom stuff. At the end I would like to be able to do this:
<pe:dynaForm id="dynaForm" value="#{dynaFormController.model}" var="data" controlKey="#{data.name}">
<pe:dynaFormControl type="input" for="txt">
<p:inputText id="txt" value="#{data.value}" required="#{data.required}" />
</pe:dynaFormControl>
<my:ajax event="keyup" listener="#{controller.authorSelected}" key="author"/>
</pe:dynaForm>
What I want to do:
Whenever the key defined in my:ajax match the controlKey of a pe:dynaFormControl, I want to attach the my:ajax client behavior to the p:inputText.
Problems encountered:
At first, I did all of this in DynaFormRenderer#encodeBody, quite convenient since var is put in the EL context. But I ended up having this exception (similar to this https://github.com/javaserverfaces/mojarra/issues/4365):
java.lang.NullPointerException
at javax.faces.component.UIComponentBase.restoreBehaviors(UIComponentBase.java:2228)
at javax.faces.component.UIComponentBase.restoreBehaviorsState(UIComponentBase.java:2203)
at javax.faces.component.UIComponentBase.restoreState(UIComponentBase.java:1623)
at javax.faces.component.UIOutput.restoreState(UIOutput.java:286)
at javax.faces.component.UIInput.restoreState(UIInput.java:1422)
at com.sun.faces.application.view.FaceletPartialStateManagementStrategy$2.visit(FaceletPartialStateManagementStrategy.java:379)
at com.sun.faces.component.visit.FullVisitContext.invokeVisitCallback(FullVisitContext.java:151)
at javax.faces.component.UIComponent.visitTree(UIComponent.java:1689)
at javax.faces.component.UIComponent.visitTree(UIComponent.java:1700)
at javax.faces.component.UIForm.visitTree(UIForm.java:371)
at javax.faces.component.UIComponent.visitTree(UIComponent.java:1700)
at com.sun.faces.application.view.FaceletPartialStateManagementStrategy.restoreView(FaceletPartialStateManagementStrategy.java:366)
at com.sun.faces.application.StateManagerImpl.restoreView(StateManagerImpl.java:138)
at com.sun.faces.application.view.ViewHandlingStrategy.restoreView(ViewHandlingStrategy.java:123)
at com.sun.faces.application.view.FaceletViewHandlingStrategy.restoreView(FaceletViewHandlingStrategy.java:591)
at com.sun.faces.application.view.MultiViewHandler.restoreView(MultiViewHandler.java:151)
at javax.faces.application.ViewHandlerWrapper.restoreView(ViewHandlerWrapper.java:353)
at com.sun.faces.lifecycle.RestoreViewPhase.execute(RestoreViewPhase.java:199)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.RestoreViewPhase.doPhase(RestoreViewPhase.java:123)
at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:198)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:658)
Then I tried to do just like o:moveComponent from Omnifaces using PreRenderViewEvent, but var is not available at this moment, in fact, calling DynaForm#getValue() always return null.
Do you have any suggestions how properly attach client behavior dynamically when var comes in the picture?
More infos: Mojarra 2.2.15 & Tomcat 8