案1
リクエストヘッダーの "Accept-Encoding"の値を "":空文字、または、 "identity" 設定
参考URL
https://siguniang.wordpress.com/2014/02/23/what-is-identity-content-encoding/
案2
以下のような実装で、自動コンテンツ解凍を無効にできそうです
HttpClient client = HttpClients.custom().disableContentCompression().build();
参考URL
https://stackoverflow.com/questions/32354232/how-to-disable-compression-handling-in-apache-httpasyncclient
https://hc.apache.org/httpcomponents-client-4.5.x/current/httpclient/apidocs/org/apache/http/impl/client/HttpClientBuilder.html#disableContentCompression()