[feature improvement] Jackson should allow real inheritance without property based polymorphism

[jhcao23]

Jackson only allow inheritance with polymorphism style such as property based definition @JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = As.PROPERTY, property="type").
However, it is necessary to consider the situation that the subclass doesn't have this property.
abstract class A {String common;}
class B extends A {String nameB;}
class C extends A {String type, extra;}
if the give json string is String content = "{ name_b: bbb }";, we want Jackson to be able to automatically cast it to B even the given result type is A:
A a = objectMapper.readValue(content, A.class);
i.e.: a instanceof B should return true and yes, A should be a B.
I believe this robust feature which requires tree-like traversal and reflection checking is what we need in a lot of real scenarios, especially when the expecting response json is an array of A which could be any subclass of A like B and C etc.

[cowtowncoder]

I think this is duplicate of #43.

[cowtowncoder]

Assuming this is a duplicate; if more information needed may modify #43 with it.