邮递员取决于不为空的字段

Question

所以我正在通过Json在Postman中设置一些数据。这是我第一次这样做，我正在研究提供的代码。

在此代码中

{
                "dependsOnFieldValue": null,
                "inputType": "Number",
                "label": "Current Year Payment",
                "required": true,
                "slug": "current-year-payment",
                "defaultValue": null,
                "readOnly": false,
                "toolTip": "To apply your payment, please type the amount you owe in the text box.",
                "unique": false,
                "options": null,
                "dependentFields": [
                    {
                        "dependsOnFieldValue": null, <------ This line here
                        "inputType": "Dropdown",
                        "label": "Current Payment Year",
                        "required": true,
                        "slug": "current-year-dropdown",
                        "defaultValue": null,
                        "readOnly": false,
                        "toolTip": "To apply your payment to a specific year, please choose the year from the drop-down menu.",
                        "unique": false,
                        "options": [
                            {
                                "name": "2017",
                                "value": "2017"
                            },
                            {
                                "name": "2018",
                                "value": "2018"
                            },
                            {
                                "name": "2019",
                                "value": "2019"
                            },
                            {
                                "name": "2020",
                                "value": "2020"
                            }
                        ],
                        "dependentFields": null
                    }
                ]
            },

我希望在下拉菜单显示上方的文本字段中输入任何内容时填充此从属字段。现在将其设置为null，但是我已经尝试过

"dependsOnFieldValue": !null,
"dependsOnFieldValue": notnull,
"dependsOnFieldValue": not-null,

有没有办法在这个dependonFieldValue上不放空？还是其他方法？