docs: @Exported(name="usage")
      public @Nonnull List<RangeItem> _getUsages() {
          List<RangeItem> r = new ArrayList<>();
          final Jenkins instance = Jenkins.getInstance();
          for (Entry<String, RangeSet> e : usages.entrySet()) {
              final String itemName = e.getKey();
              if (instance.hasPermission(Jenkins.ADMINISTER) || canDiscoverItem(itemName)) {
                  r.add(new RangeItem(itemName, e.getValue()));
              }
          }
          return r;
      }