There are cases when members deserialized from JVM classes have no JVM
signature in the proto. For example, if a member is inherited from a
built-in class (such as Map.getOrDefault in some Map implementations),
or if a member is synthesized in the compiler front-end and back-end
separately (such as enum values/valueOf). In these cases, we'll use the
naive type mapping to try to recover the signature.
#KT-16616 Fixed
#KT-17542 Fixed
