AlipayClient alipayClient = new DefaultAlipayClient("https://openapi.alipay.com/gateway.do","app_id","your private_key","json","GBK","alipay_public_key","RSA2");
ZhimaCreditPeZmgoSettleRefundRequest request = new ZhimaCreditPeZmgoSettleRefundRequest();
request.setBizContent("{" +
"  \"agreement_id\":\"ZMGO_AGR2021010510020604080000006001\"," +
"  \"partner_id\":\"2088302424614288\"," +
"  \"alipay_user_id\":\"2088302841345600\"," +
"  \"refund_amount\":3.00," +
"  \"out_request_no\":\"99202005050100930053707258\"," +
"  \"memo\":\"退款\"," +
"  \"withhold_plan_no\":\"ZMGO_WHD2021010510020603410000006001\"," +
"  \"refund_type\":\"MEMBER_FEE_REFUND\"" +
"}");
ZhimaCreditPeZmgoSettleRefundResponse response = alipayClient.execute(request);
if(response.isSuccess()){
System.out.println("调用成功");
} else {
System.out.println("调用失败");
}

{
    "sign":"ERITJKEIJKJHKKKKKKKHJEREEEEEEEEEEE",
    "zhima_credit_pe_zmgo_settle_refund_response":{
        "msg":"Service Currently Unavailable",
        "code":"20000",
        "sub_msg":"系统繁忙",
        "sub_code":"isp.unknow-error"
    }
}

{
    "code":"unknow-error",
    "message":"系统繁忙"
}