DATAJPA-510 - Fix regression when sorting by property of associated object.

The main problem was a bug in querydsl 3.3.2 that has been resolved resolved in querydsl 3.3.3 to which we just updated in in spring-data-build/#70.

Cleaner usage of querydsl API and less brittle casting. Added test case for sorting by nested association property that is wrapped in a function, e.g. lower(…).

Original pull request: #87.

src/test/java/org/springframework/data/jpa/repository/UserRepositoryTests.java

@@ -1281,6 +1281,24 @@ public class UserRepositoryTests {
 		assertThat(page.getContent().get(3), is(firstUser));
 	}
 
+	/**
+	 * @see DATAJPA-510
+	 */
+	@Test
+	public void sortByNestedAssociationPropertyWithSortOrderIgnoreCaseInPageable() {
+
+		firstUser.setManager(thirdUser);
+		thirdUser.setManager(fourthUser);
+
+		flushTestUsers();
+
+		Page<User> page = repository.findAll(new PageRequest(0, 10, //
+				new Sort(new Sort.Order(Direction.ASC, "manager.manager.firstname").ignoreCase())));
+
+		assertThat(page.getContent(), hasSize(4));
+		assertThat(page.getContent().get(3), is(firstUser));
+	}
+
 	/**
 	 * @see DATAJPA-496
 	 */