docs: public Selector createSelector()
      {
          selectorSync.lock();
          try {
              Selector selector = Selector.open();
              assert (selector != null);
              selectors.add(selector);
              return selector;
          }
          catch (IOException e) {
              throw new ZError.IOException(e);
          }
          finally {
              selectorSync.unlock();
          }
      }