protected void preValidate(FacesContext context) {
        if (isNestedWithinIterator()) {
            setDataModel(null);
        }
    }
Called by {@link jakarta.faces.component.UIData#visitTree} to determine whether or not the
<code>visitTree</code> implementation should visit the rows of UIData
or by manipulating the row index before visiting the components themselves.

Once we have the appropriate Visit hints for state saving, this method
will become obsolete.

@param ctx the <code>FacesContext</code> for the current request

@return true if row index manipulation is required by the visit to this
 UIData instance
primefaces/src/main/java/org/primefaces/component/patch/UIDataPatch.java