MongoDB _id is returned as null when t.*, t._id is used in the projection

By default, and choice of implementation the _id is not visible when using

select * from mongo.db.collection c

and this is OK

However, if I want to return the _id I need to specify it in the projection

select c._id , c.name from mongo.db.collection c

but if I want "all the column" I would like to be able to write:

select c._id , c.* from mongo.db.collection c

but this return "NULL" for the _id column