Record field doesn't accept default value if field type is union and the type of default value is pre-defined name

{
    "name": "record1",
    "type": "record",
    "fields": [
        {
            "name": "f1",
            "type": {
                "name": "record2",
                "type": "record",
                "fields": [
                    {
                        "name": "f1_1",
                        "type": "int"
                    }
                ]
            }
        },  {
            "name": "f2",
            "type": ["record2", "int"],
            "default": {
                "f1_1": 100
            }
        }
    ]
}

Error: One union type Ref must match the `default`'s value type Map