public void ensureIndex(DBObject keys, String name) throws MongoException {
        ensureIndex(keys, name, false);
    }
public void ensureIndex ( DBObject keys , String name ) throws MongoException { ensureIndex ( keys , name , false ) ; }
calls {@link DBCollection#ensureIndex(com.mongodb.DBObject, java.lang.String, boolean)} with unique=false

@param keys fields to use for index
@param name an identifier for the index
@throws MongoException If an error occurred