Httpclient 请求weblogic的HttpServlet 返回的Response中Header不一致问题

大家好，开发过程中遇到个问题 ，我做的是CS项目，在客户端用Httpclient 请求weblogic的HttpServlet 返回的HttpServletResponse用了gzip压缩结果，但是在客户端接收时解压抛异常：java.util.zip.ZipException: Not in GZIP format

server端设置了Header 并且压缩结果流

            response.setHeader("Content-Type", "text/html;charset=UTF-8");
            response.setHeader("Content-Encoding", "gzip");
            gzipstream = new GZIPOutputStream(output);

客户端代码如下
CloseableHttpResponse response = defHttpclient.execute(httppost);

            if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
                    InputStream inputStream = response.getEntity().getContent();
                    StringBuffer sb = new StringBuffer();
                    GZIPInputStream gzin = new GZIPInputStream(inputStream);
                    InputStreamReader isr = new InputStreamReader(inputStream, charSet);
                    String tempbf;
                    long test3 = System.currentTimeMillis();
                    while ((tempbf = br.readLine()) != null) {
                        sb.append(tempbf);
                    }
                    text_msg = sb.toString();
                                        try {
                        isr.close();
                        gzin.close();
                        inputStream.close();
                    } catch (Exception ex) {
                        logger.error("class Request : when inputStream byteOut", ex);
                    }
            }

会在这一行报错
GZIPInputStream gzin = new GZIPInputStream(inputStream);
通过这个方法发现
Header headers[] = response.getAllHeaders();
获得的Header中并没有服务端设置的setHeader("Content-Encoding", "gzip");

请大佬们帮忙分析分析