Why h:panelGroup with dynamic id launch java.lang.NullPointerException (JSF)?

Question

I am working with JSF 2.2 and I would like to have h:panelGroup in a h:column but the page doesn't load. The xhtml indicates the following exception:

/view/index.xhtml @120,124 id="pgEliminarFuncion#{estrategiaBean.atributoString(atributo)}" /view/strat.xhtml @120,124 id="pgEliminarFuncion#{estrategiaBean.atributoString(atributo)}": java.lang.NullPointerException.

I have the following xhtml code (where everything works out fine):

<h:dataTable value="#{estrategiaBean.funcionesDeParte}" var="atributo">
    <h:column>
        #{estrategiaBean.atributoString(atributo)}
    </h:column>
</h:dataTable>

When I change the xhtml code to...

<h:dataTable value="#{estrategiaBean.funcionesDeParte}" var="atributo">
    <h:column>
        <h:panelGroup id="pgEliminarFuncion#{estrategiaBean.atributoString(atributo)}">
            hello!
        </h:panelGroup>
    </h:column>
</h:dataTable>

... The page doesn't load.

How can I add correctly h:panelGroup to my first code?

Thank you!