If some java class has multiple supertypes then we need to collect
overriddens from all those types directly, even if superTypeScope
(which is FirTypeIntersectionScope in this case) returns only
one symbol from one of this types (not intersection one)
This is needed to proper enhancement in cases when some type occurs
multiple times in supertypes graph with different nullability
of arguments:
class ConcurrentHashMap<K, V> : AbstractMap<K!, V!>, MutableMap<K, V>
If we try to find method `get(key: K): V` supertype scope returns
`AbstractMap.get(key: K!): V!` (because it actually overrides
`MutableMap(key: K): V?`), but we need to get both symbols to
properly enhance types for `ConcurrentHashMap.remove`
- Add utilities to add new attribute to ConeAttributes
- Get rid of FlexibleNullability attribute (it can be easily inferred
for any flexible type at any moment)
- Fix determining of EnhancedNullability attribute
Vladimir Sukharev