How does preferences properties sort

hello,
I hope ‘username’ is before ‘password’, what should I do? and I want to know the sorting rules here
image

here are my code:

export const LdpPreferenceSchema: PreferenceSchema = {
    type: 'object',
    scope: 'resource',
    overridable: true,
    properties: {

        'ldp.模板工程服务器.username': {
            type: 'string',
            default: '',
            description: '连接模板工程服务器 sftp 用户名',
            overridable: false,
        },

        'ldp.模板工程服务器.password': {
            type: 'string',
            default: '',
            description: '连接模板工程服务器 sftp 密码',
            overridable: false,
        },
    },
};

@gaomin the preferences are sorted alphabetically (localeCompare) when displayed in the preferences-view.

ok, thanks a lot.