Verify proper sort handling even if HQL query already has ORDER BY a native function.

Introduce test case proving that apply a Sort to an HQL query with an already-existing "order by function()" is handled properly.

Resolves #2862.

spring-data-jpa/src/test/java/org/springframework/data/jpa/repository/query/HqlQueryTransformerTests.java

@@ -784,6 +784,15 @@ class HqlQueryTransformerTests {
 				+ "from foo f", sort)).endsWith("order by f.age desc");
 	}
 
+	@Test // GH-2862
+	void sortProperlyAppendsToExistingOrderByWithFunction() {
+
+		assertThat(createQueryFor(
+				"select e from SampleEntity e  where function('nativeFunc', ?1) > 'testVal'  order by function('nativeFunc', ?1)",
+				Sort.by(Sort.Order.desc("age")))).isEqualTo(
+						"select e from SampleEntity e where function('nativeFunc', ?1) > 'testVal' order by function('nativeFunc', ?1), e.age desc");
+	}
+
 	private void assertCountQuery(String originalQuery, String countQuery) {
 		assertThat(createCountQueryFor(originalQuery)).isEqualTo(countQuery);
 	}