.net 7 BadRequestObjectResult uses CamelCase Policy - json

Question

I have configured the JsonSerializerOptions's PropertyNamingPolicy as null, OData all results gets as expected, but BadRequestObjectResult is still using camelcase policy.
builder.Services.AddControllers()
.AddJsonOptions(options => {
options.JsonSerializerOptions.PropertyNamingPolicy = null; // to don't change property names lowercase
options.JsonSerializerOptions.DictionaryKeyPolicy = null;
})
protected ActionResult ValidationFailed()
{
var err = new ODataError
{
Message = "Validation error",
Details = ModelState.ToDictionary(
kvp => kvp.Key, //.ToCamelCase(),
kvp => kvp.Value.Errors.Select(e => e.ErrorMessage).ToArray()
).Select(e => new ODataErrorDetail() {
ErrorCode = e.Key,
Message = string.Join("\n", e.Value.ToArray())
}).ToList()
};
return new BadRequestObjectResult(err);
}
{
"error": {
"code": "",
"message": "Validation error",
"details": [
{
"code": "person.corpid",
"message": "Corpid field must be value"
}
]
}
}
I want to get all results without changed like following.
{
"Error": {
"Code": "",
"Message": "Validation error",
"Details": [
{
"Code": "Person.Corpid",
"Message": "Corpid field must be value"
}
]
}
}