code: public static HttpClient<ByteBuf, ByteBuf> newClient(ConnectionProviderFactory<ByteBuf, ByteBuf> providerFactory,
                                                           Observable<Host> hostStream) {
          return HttpClientImpl.create(providerFactory, hostStream);
      }
docs: Creates a new HTTP client instance using the supplied connection provider.
  
  @param providerFactory {@link ConnectionProviderFactory} for the client.
  @param hostStream Stream of hosts for the client.
  
  @return A new {@code HttpClient} instance.