Proposal: Support for "default" values, output document with defaults, accept "default" values for "required" fields

[Garagoth]

Given the schema:

{
    "$id": "https://jschon.dev/schema",
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "required": ["p1", "p2"],
    "properties": {
        "p1": {"type": "string", "default": "def_val"},
        "p2": {"type": "integer", "default": 7, "minimum": 5},
        "p3": {"type": "string"}
    }
}

following document does not validate:

{
    "p2": 6,
    "p3": "test_p3"
}

Finally, as a result of validation, I would like to be able to get document that was validated extended with all fields with default values that were not present in original document.