What kind of change does this PR introduce?
Bug fix
What is the current behavior?
Interface 'UserDocument' cannot simultaneously extend types 'User' and 'Document'.
Named property '_id' of types 'User' and 'Document' are not identical.
What is the new behavior (if this is a feature change)?
Error is fixed
Other information:
The _id:any attribute needs to be changed to _id: mongodb.ObjectID;