@Override
    public T fetchOne() throws NonUniqueResultException {
        queryMixin.setUnique(true);
        if (queryMixin.getMetadata().getModifiers().getLimit() == null) {
            limit(2L);
        }
        return uniqueResult(iterate());
    }
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