`limit` in `FetchableFluentQueryBySpecification` addes duplicate `order by` clause

[JingBh]

As this code in FetchableFluentQueryBySpecification shows, adding a limit applies the current sorting again.

spring-data-jpa/spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/support/FetchableFluentQueryBySpecification.java

Lines 96 to 103 in b00220b

	@Override
	public FetchableFluentQuery<R> limit(int limit) {
	Assert.isTrue(limit >= 0, "Limit must not be negative");
	return new FetchableFluentQueryBySpecification<>(spec, entityType, resultType, this.sort.and(sort), limit,
	properties, finder, scroll, countOperation, existsOperation, entityManager, projectionFactory);
	}

In my application, this is causing duplicate order by clause to be included in the SQL generated like order by q1_0."id" desc,q1_0."id" desc, as I call .sortBy first, and then .limit.

Of course, it's easy to fix on the application's side by calling .limit first, but I think this is a bug in the framework, as the other class FetchableFluentQueryByPredicate implementing the same interface does not have this behavior.

[quaff]

Good catch, I think it's better to force using this reference if same name of field and local variable present.