为什么在我的JSON模式中没有遵守必填字段?

我正在为一个公司项目一步一步地自学JSON模式验证(用C#),我已经达到了学习字段要求的地步,但我看到的结果似乎不符合我的“必填字段”规范,我可以用手来弄清楚原因。

这是我保存在一个名为“TestJsonSchema.txt”的文件中的模式。。。

{
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "$id": "https://example.com/product.schema.json",
    "title": "Person",
    "description": "Simple person for testing schema validation",
    "type": "object",
    "properties": {
        "FirstName": {
            "description": "The person's first name.",
            "type": "string"
        },
        "LastName": {
            "description": "The person's last name.",
            "type": "string"
        },
        "Age": {
            "description": "Age of the person in years.",
            "type": "integer",
            "exclusiveMinimum": 18
        }
    },
    "required": ["LastName", "Age"]
}

…这是测试程序。。。

using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
using Newtonsoft.Json.Schema;

   public class Person
   {
       public string FirstName { get; set; }
       public string LastName { get; set; }
       public int Age { get; set; }
   }

   public class Program
   {
       public static void Main(string[] args)
       {
           string schemaFilePath = @"C:\testtest\TestJsonSchema.txt";
           JSchema schema = JSchema.Parse(File.ReadAllText(schemaFilePath));

           // Should be valid.
           Person fullPerson = new Person()
           {
               FirstName = "John",
               LastName = "Doe",
               Age = 25
           };

           // I expect this to be valid as there's a LName and age.
           Person noFNamePerson = new Person()
           {
               LastName = "Teller",
               Age = 30
           };

           // I expect this to be invalid as there's no LName
           Person noLNamePerson = new Person()
           {
               FirstName = "Madonna",
               Age = 56
           };

           // I expect this to be valid as both teh LastName and Age are populated.
           Person BlankFNamePerson = new Person()
           {
               FirstName = "",
               LastName = "Mason",
               Age = 49
           };

           // I honestly don't know whether this should or shouldn't be valid since
           // the required LastName is blank.
           // (My first time with these validity checks.  Hence all these test cases)
            Person BlankLNamePerson = new Person()
           {
               FirstName = "Cher",
               LastName = "",
               Age = 120
           };
           
           JObject fullObj = JObject.Parse(JsonConvert.SerializeObject(fullPerson));
           JObject noFNameObj = JObject.Parse(JsonConvert.SerializeObject(noFNamePerson));
           JObject noLNameObj = JObject.Parse(JsonConvert.SerializeObject(noLNamePerson));
           JObject blankFNameObj = JObject.Parse(JsonConvert.SerializeObject(BlankFNamePerson));
           JObject blankLNameObj = JObject.Parse(JsonConvert.SerializeObject(BlankLNamePerson));

           bool fullValid = fullObj.IsValid(schema);               // Coming up true.  EXPECTED
           bool noFNameValid = noFNameObj.IsValid(schema);         // Coming up false.  !! WHY?? !!
           bool noLNameValid = noLNameObj.IsValid(schema);         // Coming up false.  EXPECTED
           bool blankFNameValid = blankFNameObj.IsValid(schema);   // Coming up true.  EXPECTED
           bool blankLNameValid = blankLNameObj.IsValid(schema);   // Coming up true.  NOT SURE IF CORRECT.

           // THESE ARE MY QUICK AND DIRTY WAYS OF FINDING OUT WHAT IS AND ISN'T VALID.
           Console.WriteLine("Full person is valid: " + fullValid);
           Console.WriteLine("No First Name person is valid: " + noFNameValid);
           Console.WriteLine("No Last Name person is valid: " + noLNameValid);
           Console.WriteLine("Blank First Name person is valid: " + blankFNameValid);
           Console.WriteLine("Blank Last Name person is valid: " + blankLNameValid);            
       }
   }

为了严格审查,以下是无名字者和空白名字者的转换JSON。。。

没有名字(出现无效)

{"FirstName":null,"LastName":"Teller","Age":30}

空白名字(即将生效)

{"FirstName":"","LastName":"Mason","Age":49}

所以,长话短说, 为什么没有名字的人即使有必填字段也无效?此外,空白字符串(如空白名字JSON)的存在是否足以满足必填字段?

注: 这些有效/无效结果与我 去除 模式中的“必需”项。这就是为什么我首先提出了这个问题;我不确定我是否使用不当。

谢谢。