通过提取发送时，表单值似乎为空

Question

const fetch = require('node-fetch');
const FormData = require('form-data');
async function check () {
    const form = new FormData();
    form.append('merchantIdentifier', 'b19e8f103bce406cbd3476431b6b7973')
    form.append('orderId', 'ZPK12345' )
    form.append('mode', 0)
    form.append('checksum', '94681259256bc24e3c6881fe85e0fd61cf1b41a0e650c9ca6b7b7fe7ae510af4')
    try {
        const result =  await fetch(`http://zaakpaystaging.centralindia.cloudapp.azure.com:8080/checktransaction?v=5`, {
            method: 'POST',
            headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
            body: form
        })
        const data = await result.text()
        console.log(data)
    } catch (error) {
        console.log(error);
    }
}

check()

通过表单数据将数据发送到http://zaakpaystaging.centralindia.cloudapp.azure.com:8080/checktransaction?v=5，但响应表单值为空