class T::Props::Decorator

def prop_nilable?(cls, rules)
`prop` and `const` do not `T::Utils::coerce the type of the prop if it is a `Module`,
e the bare `NilClass` check.
ls::Nilable.is_union_with_nilclass(cls) || ((cls == T.untyped || cls == NilClass) && rules.key?(:default) && rules[:default].nil?)