How can I get headers in this script as an array?

Question

Java

Tell me how can I get all the headers in the form of an array in this script?

import java.net.URI;
import java.net.URISyntaxException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import org.apache.http.client.fluent.Async;
import org.apache.http.client.fluent.Content;
import org.apache.http.client.fluent.Request;
import org.apache.http.client.utils.URIBuilder;
import org.apache.http.concurrent.FutureCallback;
 
 
/**
 * Java mass loader
 */
public class MassLoader {
 
    /**
     * Main method
     *
     * @param args
     */
    public static void main(String[] args) {
 
        URIBuilder builder = new URIBuilder();
        builder.setScheme("http").setHost("google.com").setPath("/");
 
        URI requestURL = null;
        try {
            requestURL = builder.build();
        } catch (URISyntaxException use) {}
 
        ExecutorService threadpool = Executors.newFixedThreadPool(100);
        Async async = Async.newInstance().use(threadpool);
        final Request request = Request.Get(requestURL);
 
        for(int i=0; i < 100; i++) {
            Future<Content> future = async.execute(request, new FutureCallback<Content>() {
                public void failed (final Exception e) {
                    System.out.println(e.getMessage() +": "+ request);
                }
 
                public void completed (final Content content) {
 
                    System.out.println("Request completed: "+ request);
                    System.out.println("Response:\n"+ content.asString());
                }
 
                public void cancelled () {
                    System.out.print("Cancelled");
                }
            });
        }
    }
 
}