Get Gziped content from CloseableHttpAsyncClient

Question

I am working in an environment where I am currently required to only use apache hc libraries. More specifically,

    <dependency>
        <groupId>org.apache.httpcomponents</groupId>
        <artifactId>httpasyncclient</artifactId>
        <version>4.1.3</version>
    </dependency>

Although I am trying to use an instance of CloseableHttpAsyncClient as the client for Spring's AsyncRestTemplate. I wrote the following example to experiment with fetching gzipped content from a local server.

I am able to verify that server supports compressed response using httpie as you can see below.

$ http --print=Hhb :8081/hello
GET /hello HTTP/1.1
Accept: */*
Accept-Encoding: gzip, deflate
Connection: keep-alive
Host: localhost:8081
User-Agent: HTTPie/0.9.9

HTTP/1.1 200
Content-Encoding: gzip
Content-Type: application/json;charset=UTF-8
Date: Tue, 06 Mar 2018 22:05:25 GMT
Transfer-Encoding: chunked
Vary: Accept-Encoding

[
    1,
    2,
    3,
    4,
    5
]

Now when I try to read using a sample code for CloseableHttpAsyncClient, it does not work very clearly. I am required to decompress the gzip content even after adding the ResponseInterceptor.

// org.slf4j.Logger LOGGER

// Imports
import org.apache.http.Header;
import org.apache.http.HeaderElement;
import org.apache.http.HttpEntity;
import org.apache.http.HttpHost;
import org.apache.http.HttpResponse;
import org.apache.http.HttpResponseInterceptor;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.entity.GzipDecompressingEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.nio.client.CloseableHttpAsyncClient;
import org.apache.http.impl.nio.client.HttpAsyncClients;
import org.apache.http.message.BasicHeader;
import org.apache.http.ssl.SSLContextBuilder;
import org.apache.http.util.EntityUtils;


// Demo Code

CloseableHttpAsyncClient httpAsyncClient = HttpAsyncClients.custom()
    .setDefaultRequestConfig(
        RequestConfig.custom()
            .setContentCompressionEnabled(false)
            .build())
    .setDefaultHeaders(Collections.singleton(new BasicHeader("Accept-Encoding", "gzip")))
    .setProxy(new HttpHost("localhost", 8080))
    .addInterceptorFirst((HttpResponseInterceptor) (response, context) -> {
        HttpEntity entity = response.getEntity();
        Header contentEncodingHeader = entity.getContentEncoding();

        if (contentEncodingHeader != null) {
            HeaderElement[] encodings = contentEncodingHeader.getElements();
            for (int i = 0; i < encodings.length; i++) {
                if (encodings[i].getName().equalsIgnoreCase("gzip")) {
                    response.setEntity(new GzipDecompressingEntity(entity));
                    break;
                }
            }
        }

    })
    .build();

httpAsyncClient.start();

HttpGet request = new HttpGet("http://localhost:8081/hello");
Future<HttpResponse> future = httpAsyncClient.execute(request, null);
HttpResponse httpResponse = future.get();

LOGGER.info(decompress(EntityUtils.toByteArray(httpResponse.getEntity())));

// Output:
// [1,2,3,4,5]

where decompress is a small utility i wrote to do the decompression.

public static String decompress(byte[] compressedBytes) throws IOException {
    ByteArrayInputStream bis = new ByteArrayInputStream(compressedBytes);
    GZIPInputStream gis = new GZIPInputStream(bis);
    BufferedReader br = new BufferedReader(new InputStreamReader(gis, "UTF-8"));
    StringBuilder sb = new StringBuilder();
    String line;
    while((line = br.readLine()) != null) {
        sb.append(line);
    }
    br.close();
    gis.close();
    bis.close();
    return sb.toString();
}

Now what I expected is EntityUtils.toString(httpResponse.getEntity()) should directly return me the uncompressed response in string but it does not and I have to manually decompress the content. I suspected the decompression is the job of GzipDecompressingEntity but for some reason it doesn't play well (could it be because the response is chunked?)

Is there a way i can do the decompression in the async fashion either by using GzipDecompressingEntity correctly or manually doing the decompression in an async fashion so that when i do future.get() it has the response that is uncompressed ?