java HttpUrlConnection无法使用setRequestProperty

Question

有人对发生的事情有解释吗

下面的代码片段显示了我是如何准备连接的

问题是：

什么时候 connection.setRequestProperty("Content-Type", "text/xml; charset=utf-8"); 添加后，我会得到一个400 Bad request，但是如果我删除该行，它就会工作

@Override
protected void prepareConnection(HttpURLConnection connection)
        throws IOException {
    String userPassword = taskProperties.getCadyUser() + ":" + taskProperties.getCadyPass();
    String encodedAuthorization = new String(Base64.encode(userPassword.getBytes(StandardCharsets.UTF_8)), StandardCharsets.UTF_8);
    connection.setRequestProperty("Authorization", "Basic " + encodedAuthorization);
    connection.setRequestProperty("Content-Type", "text/xml; charset=utf-8");
    super.prepareConnection(connection);
}

工作示例：

    @Override
    protected void prepareConnection(HttpURLConnection connection)
            throws IOException {
        String userPassword = taskProperties.getCadyUser() + ":" + taskProperties.getCadyPass();
        String encodedAuthorization = new String(Base64.encode(userPassword.getBytes(StandardCharsets.UTF_8)), StandardCharsets.UTF_8);
        connection.setRequestProperty("Authorization", "Basic " + encodedAuthorization);
        super.prepareConnection(connection);
    }

有人能解释这种现象吗