Simple illustration problems with empty HttpEntities which is not returned to connections pool

EmptyHttpServer.java

import java.util.concurrent.TimeUnit;

import org.apache.http.HttpRequest;
import org.apache.http.HttpResponse;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.config.SocketConfig;
import org.apache.http.impl.bootstrap.HttpServer;
import org.apache.http.impl.bootstrap.ServerBootstrap;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
import org.apache.http.protocol.HttpContext;
import org.apache.http.protocol.HttpRequestHandler;

public class EmptyHttpServer {
    public static void main(String[] args) throws Exception {
        SocketConfig socketConfig = SocketConfig.custom()
                .setSoTimeout(15000)
                .setTcpNoDelay(true)
                .build();
        RequestConfig requestConfig = RequestConfig.custom()
                .setConnectionRequestTimeout(1000)
                .build();

        final HttpServer server = ServerBootstrap.bootstrap()
                .setListenerPort(8080)
                .setSocketConfig(socketConfig)
                .registerHandler("*", new EmptyHandler())
                .create();

        server.start();

        PoolingHttpClientConnectionManager connMgr =
            new PoolingHttpClientConnectionManager();
        connMgr.setDefaultMaxPerRoute(1);
        try (CloseableHttpClient client = HttpClients.custom()
                .setConnectionManager(connMgr)
                .setDefaultRequestConfig(requestConfig)
                .build();
            CloseableHttpResponse response1 = client.execute(
                new HttpGet("http://localhost:8080/"));
            CloseableHttpResponse response2 = client.execute(
                new HttpGet("http://localhost:8080/")))
        {
        } finally {
            server.shutdown(5, TimeUnit.SECONDS);
        }
    }

    private static class EmptyHandler implements HttpRequestHandler  {
        @Override
        public void handle(
                final HttpRequest request,
                final HttpResponse response,
                final HttpContext context)
        {
        }
    }
}