code: protected void remapRows() {
          rowMap = new HashMap<>();
          final FacesContext context = FacesContext.getCurrentInstance();
          final Map<String, Object> requestMap = context.getExternalContext().getRequestMap();
          final Collection<?> values = (Collection<?>) getValue();
          final String var = getVar();
          for (final Object obj : values) {
              requestMap.put(var, obj);
              try {
                  final String key = getRowKeyValueAsString(context);
                  rowMap.put(key, obj);
              }
              finally {
                  requestMap.remove(var);
              }
          }
      }
docs: Remaps the row keys in a hash map.