code: private void setHeaders(HttpMessage message, Map<String, String> headers) {
  		message.setHeader(RequestHeaderKey.ACCEPT, RequestHeaderValue.Accept.ALL);
  		message.setHeader(RequestHeaderKey.CONNECTION, RequestHeaderValue.Connection.KEEP_ALIVE);
  		message.setHeader(RequestHeaderKey.USER_AGENT, this.config.getUserAgent());
  
  		if (headers != null) {
  			for (String headerKey : headers.keySet()) {
  				message.setHeader(headerKey, headers.get(headerKey));
  			}
  		}
  	}
docs: 设置Http头部，同时添加上公共的类型，长连接，COS SDK标识
  
  @param message
  HTTP消息
  @param headers
  用户额外添加的HTTP头部