Should Json table have exactly same format?

Development Programming & Scripting
1

I try to import JSON table into Content Browser.
Here is correct JSON table.

[
  {
    "Name" : "John",
    "Age": "20"
  },
  {
    "Name" : "Smith",
    "Age": "66"
  }
]

I can get the JSON data with this class,

USTRUCT(BlueprintType)
struct FPersonAge : public FTableRowBase
{
  GENERATED_USTRUCT_BODY()
  UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = Person)
  int Age;
};

But, if I remove age field of one node like this,

[
  {
    "Name" : "John",
    "Age": "20"
  },
  {
    "Name" : "Smith"
  }
]

Unreal 4 (4.16) says, “Row ‘Age’ is missing an entry for ‘Smith’”,

I think Unreal treat JSON table as if CSV files so all entries have same fields,
but, to do that, JSON file become too big.(some file is more than 100Mbyte).

Can I give something like ‘default value’ for object property,
so we can remove data if it is same as ‘default value’?

Thanks.