1. DefaultDBCallback.gotDBRef() should put c.m.DBRef into object hierarchy when encountered DBPointer(0x0c) BSONType
2. DefaultDBEncoder will treat c.m.DBPointer as DBRef and send it as {$ref:"...",$id:...} to server.
1. DefaultDBCallback.gotDBRef() should put c.m.DBRef into object hierarchy when encountered DBPointer(0x0c) BSONType
2. DefaultDBEncoder will treat c.m.DBPointer as DBRef and send it as {$ref:"...",$id:...} to server.