code: @Override @Nullable
      public synchronized Host getNextHost(@NotNull Host exceptHost) {
          return getNextHost(Collections.singleton(exceptHost));
      }
docs: This behaves like {@link #getHost} in this class, and forwards to the next one
  in case the one that would be returned is the same as <code>exceptHost</code>.
  @param exceptHost The host that is not acceptable, for example because it was just used and failed.