Allow combining Sort and TypedSort using Sort.and(…).

We now retain properly the collection of orders by using accessor methods instead of relying on using the orders field. TypedSort orders are not using the orders field, instead they iterate over recorded persistent property paths.

Closes #2103
Original pull request: #2377.

src/main/java/org/springframework/data/domain/Sort.java

@@ -170,7 +170,7 @@ public class Sort implements Streamable<org.springframework.data.domain.Sort.Ord
 	}
 
 	public boolean isSorted() {
-		return !orders.isEmpty();
+		return !isEmpty();
 	}
 
 	public boolean isUnsorted() {
@@ -188,7 +188,7 @@ public class Sort implements Streamable<org.springframework.data.domain.Sort.Ord
 
 		Assert.notNull(sort, "Sort must not be null!");
 
-		ArrayList<Order> these = new ArrayList<>(this.orders);
+		ArrayList<Order> these = new ArrayList<>(this.toList());
 
 		for (Order order : sort) {
 			these.add(order);
@@ -240,7 +240,7 @@ public class Sort implements Streamable<org.springframework.data.domain.Sort.Ord
 
 		Sort that = (Sort) obj;
 
-		return this.orders.equals(that.orders);
+		return toList().equals(that.toList());
 	}
 
 	/*
@@ -261,7 +261,7 @@ public class Sort implements Streamable<org.springframework.data.domain.Sort.Ord
 	 */
 	@Override
 	public String toString() {
-		return orders.isEmpty() ? "UNSORTED" : StringUtils.collectionToCommaDelimitedString(orders);
+		return isEmpty() ? "UNSORTED" : StringUtils.collectionToCommaDelimitedString(orders);
 	}
 
 	/**
@@ -272,7 +272,7 @@ public class Sort implements Streamable<org.springframework.data.domain.Sort.Ord
 	 */
 	private Sort withDirection(Direction direction) {
 
-		return Sort.by(orders.stream().map(it -> new Order(direction, it.getProperty())).collect(Collectors.toList()));
+		return Sort.by(stream().map(it -> new Order(direction, it.getProperty())).collect(Collectors.toList()));
 	}
 
 	/**

src/test/java/org/springframework/data/domain/SortUnitTests.java

@@ -25,6 +25,7 @@ import java.util.Collection;
 import org.junit.jupiter.api.Test;
 import org.springframework.data.domain.Sort.Direction;
 import org.springframework.data.domain.Sort.Order;
+import org.springframework.data.geo.Circle;
 
 /**
  * Unit test for {@link Sort}.
@@ -33,6 +34,7 @@ import org.springframework.data.domain.Sort.Order;
  * @author Kevin Raymond
  * @author Thomas Darimont
  * @author Mark Paluch
+ * @author Hiufung Kwok
  */
 class SortUnitTests {
 
@@ -186,6 +188,17 @@ class SortUnitTests {
 				.containsExactly(Order.by("nesteds.firstname"));
 	}
 
+	@Test // #2103
+	void allowsCombiningTypedSorts() {
+
+		assertThat(Sort.sort(Circle.class).by(Circle::getCenter) //
+				.and(Sort.sort(Circle.class).by(Circle::getRadius))) //
+						.containsExactly(Order.by("center"), Order.by("radius"));
+
+		assertThat(Sort.by("center").and(Sort.sort(Circle.class).by(Circle::getRadius))) //
+				.containsExactly(Order.by("center"), Order.by("radius"));
+	}
+
 	@Getter
 	static class Sample {
 		Nested nested;