HystrixCommand send http error

import com.netflix.niws.client.http.HttpClientRequest;
import com.netflix.niws.client.http.HttpClientRequest.Verb;
import com.netflix.niws.client.http.HttpClientResponse;
import com.netflix.niws.client.http.RestClient;
import org.apache.http.entity.StringEntity;
import org.apache.http.entity.ContentType;

public class AddRSSCommand extends HystrixCommand<String> {

    private final String url;

    public AddRSSCommand() {
        super (Setter.withGroupKey(HystrixCommandGroupKey.Factory.asKey(RSSConstants.HYSTRIX_RSS_MUTATIONS_GROUP))
                .andCommandKey(HystrixCommandKey.Factory.asKey(RSSConstants.HYSTRIX_RSS_ADD_COMMAND_KEY))
                .andThreadPoolKey(HystrixThreadPoolKey.Factory.asKey(RSSConstants.HYSTRIX_RSS_THREAD_POOL)));
    }

    @Override
    protected String run() {
        String jsonString = "{username: 'Hermione', password: 'Granger'}"
        StringEntity se = new StringEntity(jsonString, ContentType.APPLICATION_JSON);

        try {
            RestClient client = (RestClient) ClientFactory.getNamedClient(RSSConstants.MIDDLETIER_REST_CLIENT);

            HttpClientRequest request = HttpClientRequest
                    .newBuilder()
                    .setVerb(Verb.POST)
                    .setUri(new URI("/"
                            + RSSConstants.MIDDLETIER_WEB_RESOURCE_ROOT_PATH
                            + RSSConstants.RSS_ENTRY_POINT
                            + "?url=" + url))
                    .setEntity(se);
                    .build();

            HttpClientResponse response = client.executeWithLoadBalancer(request);
            return IOUtils.toString(response.getRawEntity(), Charsets.UTF_8);
        } catch (Exception exc) {
            throw new RuntimeException("Exception occurred when adding a RSS feed", exc);
        }
    }

}