Support NullHandling in JSqlParserQueryEnhancer.

Closes #3886

Author: mp911de

spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/query/JSqlParserQueryEnhancer.java

@@ -501,6 +501,15 @@ private static OrderByElement getOrderClause(Set<String> joinAliases, Set<String
 				: property;
 		Expression orderExpression = order.isIgnoreCase() ? getJSqlLower(reference) : new Column(reference);
 		orderByElement.setExpression(orderExpression);
+
+		switch (order.getNullHandling()) {
+			case NULLS_FIRST -> orderByElement.setNullOrdering(OrderByElement.NullOrdering.NULLS_FIRST);
+			case NULLS_LAST -> orderByElement.setNullOrdering(OrderByElement.NullOrdering.NULLS_LAST);
+			default -> {
+				// do nothing
+			}
+		}
+
 		return orderByElement;
 	}
 

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

@@ -25,6 +25,8 @@
 import org.junit.jupiter.params.provider.Arguments;
 import org.junit.jupiter.params.provider.MethodSource;
 import org.springframework.data.domain.Sort;
+import org.springframework.data.projection.SpelAwareProxyProjectionFactory;
+import org.springframework.data.repository.query.ReturnedType;
 
 /**
  * TCK Tests for {@link JSqlParserQueryEnhancer}.
@@ -51,6 +53,19 @@ void shouldApplySorting() {
 		assertThat(sql).isEqualTo("SELECT e FROM Employee e ORDER BY e.foo ASC, e.bar ASC");
 	}
 
+	@Test // GH-3886
+	void shouldApplySortingWithNullsPrecedence() {
+
+		QueryEnhancer enhancer = createQueryEnhancer(DeclaredQuery.of("SELECT e FROM Employee e", true));
+
+		String sql = enhancer.rewrite(new DefaultQueryRewriteInformation(
+				Sort.by(Sort.Order.asc("foo").with(Sort.NullHandling.NULLS_LAST),
+						Sort.Order.desc("bar").with(Sort.NullHandling.NULLS_FIRST)),
+				ReturnedType.of(Object.class, Object.class, new SpelAwareProxyProjectionFactory())));
+
+		assertThat(sql).isEqualTo("SELECT e FROM Employee e ORDER BY e.foo ASC NULLS LAST, e.bar DESC NULLS FIRST");
+	}
+
 	@Test // GH-3707
 	void countQueriesShouldConsiderPrimaryTableAlias() {