The implicit EL object #{component}
refers to the current component, which is in the case of
<h:outputText value="#{component.clientId}" />
the <h:outputText>
itself!
If you intend to print the client ID of another component, then you need to bind the component instance to an unique variable in the view by binding
, so that you can reference it anywhere else in the same view.
<h:panelGroup id="listItem" binding="#{listItem}">
<h:outputText value="#{listItem.clientId}" />
</h:panelGroup>