PrimeFaces: WARNING: Target model Type is no a Collection or Array

WARNING: Target model Type is no a Collection or Array
javax.faces.FacesException: Target model Type is no a Collection or Array
 at com.sun.faces.renderkit.html_basic.MenuRenderer.convertSelectManyValuesForModel(MenuRenderer.java:392)
 at com.sun.faces.renderkit.html_basic.MenuRenderer.convertSelectManyValue(MenuRenderer.java:129)

Solution: should have used p:selectOneRadio (accepts only one selection) instead of p:selectManyCheckbox (accepts one or more selections)