Macro validate_spawn_args

macro_rules! validate_spawn_args {
    () => { ... };
    (name) => { ... };
    (on_exit) => { ... };
    (request_capabilities) => { ... };
    (grant_capabilities) => { ... };
    (public) => { ... };
    ($first:ident, $($rest:ident),+ $(,)?) => { ... };
    ($invalid:ident $(, $($rest:tt)*)?) => { ... };
}