Ability to check the form 'key=null' by default, instead of triggering the default value of key only if the key is not passed

[skyeXxx]

{"body_type": "2",
"method": 2,
"domain": "",
"version":null
}version: str = Field(default='V1.0') cannot be triggered using the default value；b
but ,
{"body_type": "2",
"method": 2,
"domain": ""
} Can use
Hopefully it will be supported by default instead of using @validator