@property<EOL><INDENT>def on_by_default(self):<DEDENT>
return self._on_by_default<EOL>
Gets the on_by_default of this V1ModifierOption.
If true, the modifier option is the default option in a modifier list for which selection_type is SINGLE.

:return: The on_by_default of this V1ModifierOption.
:rtype: bool