@Nullable
    public DBObject findOne(final Object id, final DBObject projection) {
        return findOne(new BasicDBObject("_id", id), new DBCollectionFindOptions().projection(projection));
    }
@Nullable
    public DBObject findOne(final Object id, final DBObject projection) {
        return findOne(new BasicDBObject("_id", id), new DBCollectionFindOptions().projection(projection));
    }
@ Nullable public DBObject findOne ( final Object id , final DBObject projection ) { return findOne ( new BasicDBObject ( "_id" , id ) , new DBCollectionFindOptions ( ) . projection ( projection ) ) ; }
Get a single document from collection by '_id'.

@param id         value of '_id' field of a document we are looking for
@param projection specifies which projection MongoDB will return from the documents in the result set.
@return A document that satisfies the query specified as the argument to this method.
@mongodb.driver.manual tutorial/query-documents/ Querying
Get a single document from collection by _id .