xdrgen: XDR width for optional_data type

    spec: _XdrTypeSpecifier

    template: str = "optional_data"

    def max_width(self) -> int:

        """Return width of type in XDR_UNITS"""

        return 1

    def symbolic_width(self) -> List:

        """Return list containing XDR width of type's components"""

        return ["XDR_bool"]

    def __post_init__(self):

        structs.add(self.name)

        pass_by_reference.add(self.name)

        max_widths[self.name] = self.max_width()

        symbolic_widths[self.name] = self.symbolic_width()

@dataclass