docs: public static Set getSubmittedValuesAsSet(FacesContext context,
              UIComponent component, Converter converter,
              UISelectMany uiSelectMany)
      {
          Object submittedValues = uiSelectMany.getSubmittedValue();
          if (submittedValues == null)
          {
              return null;
          }
  
          if (converter != null)
          {
              converter = new PassThroughAsStringConverter(converter);
          }
  
          return internalSubmittedOrSelectedValuesAsSet(context, component,
                  converter, uiSelectMany, submittedValues, false);
      }