Select a planet on the left. One the right side, you can select one of the moons.
The planets are added with
<f:selectItems value="#{selectOneRadioController.planets}"/>
.
The radiogroup of the planets also contain a
<f:ajax render="moonradio">
element,
which allows to rerender the radiogroup with the ID 'moonradio' every time, the value changed in the
planet-radiogroup.