if isinstance(va, str) and va:
            return va
        return None

    @property
    def serialization_alias(self) -> Union[str, None]:
        sa = self.field_info.serialization_alias
        return sa or None

    @property
    def required(self) -> bool:
        return self.field_info.is_required()

    @property
    def default(self) -> Any: