Selections: radio group sorting is broken

Adding sorting configuration to a RadioGroup field does not work (anymore).

Reproduction path:

• create a Value list document with value labels "A", "B", "C".
• add a RadioGroup field to a document type and set the sortOrder to "descending"
• in the preview of the document type you already see it: the order remains A-B-C instead of the other way around

Reason: the value list is retrieved twice by the RadioGroup plugin, once for the selected value and once for the list of options. The first time the list is sorted correctly, but the second time in org.onehippo.forge.selection.frontend.plugin.sorting.SortHelper#sort line 47 the listItemComparator object is not null and then the sorting is skipped, because it is inside the if-block.

This may be a regression: check if we need backports.