@Override
    public QueryResults<T> fetchResults() {
        @SuppressWarnings("unchecked") // This is the built type
        Expression<T> projection = (Expression<T>) queryMixin.getMetadata().getProjection();
        long count = queryEngine.count(getMetadata(), iterables);
        if (count > 0L) {
            List<T> list = queryEngine.list(getMetadata(), iterables, projection);
            return new QueryResults<T>(list, getMetadata().getModifiers(), count);
        } else {
            return QueryResults.<T>emptyResults();
        }
    }
Define a left join from the Map typed path to the alias

@param <P> type of expression
@param target target of the join
@param alias alias for the joint target
@return current object
querydsl-collections/src/main/java/com/querydsl/collections/AbstractCollQuery.java