fix: set the correct database id on the key parent when calling Key#getParent (#1457)

* fix: set database ID on parent key

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

---------

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Author: nzhenry

google-cloud-datastore/src/main/java/com/google/cloud/datastore/IncompleteKey.java

@@ -91,9 +91,11 @@ public Key getParent() {
     PathElement parent = ancestors.get(ancestors.size() - 1);
     Key.Builder keyBuilder;
     if (parent.hasName()) {
-      keyBuilder = Key.newBuilder(getProjectId(), parent.getKind(), parent.getName());
+      keyBuilder =
+          Key.newBuilder(getProjectId(), parent.getKind(), parent.getName(), getDatabaseId());
     } else {
-      keyBuilder = Key.newBuilder(getProjectId(), parent.getKind(), parent.getId());
+      keyBuilder =
+          Key.newBuilder(getProjectId(), parent.getKind(), parent.getId(), getDatabaseId());
     }
     String namespace = getNamespace();
     if (namespace != null) {

google-cloud-datastore/src/test/java/com/google/cloud/datastore/IncompleteKeyTest.java

@@ -25,15 +25,17 @@
 
 public class IncompleteKeyTest {
 
-  private static IncompleteKey pk1, pk2, pk4;
-  private static Key parent1;
+  private static IncompleteKey pk1, pk2, pk4, pk5;
+  private static Key parent1, parent2;
 
   @Before
   public void setUp() {
     pk1 = IncompleteKey.newBuilder("ds", "kind1").build();
     parent1 = Key.newBuilder("ds", "kind2", 10).setNamespace("ns").build();
+    parent2 = Key.newBuilder("ds", "kind2", 10, "test-db").setNamespace("ns").build();
     pk2 = IncompleteKey.newBuilder(parent1, "kind3").build();
     pk4 = IncompleteKey.newBuilderWithDatabaseId("ds", "kind3", "test-db").build();
+    pk5 = IncompleteKey.newBuilder(parent2, "kind4").build();
   }
 
   @Test
@@ -59,12 +61,18 @@ public void testBuilders() {
     assertEquals("test-db", pk4.getDatabaseId());
     assertEquals("kind3", pk4.getKind());
     assertTrue(pk4.getAncestors().isEmpty());
+
+    assertEquals("ds", pk5.getProjectId());
+    assertEquals("test-db", pk5.getDatabaseId());
+    assertEquals("kind4", pk5.getKind());
+    assertEquals(parent2.getPath(), pk5.getAncestors());
   }
 
   @Test
   public void testParent() {
     assertNull(pk1.getParent());
     assertEquals(parent1, pk2.getParent());
+    assertEquals(parent2, pk5.getParent());
     Key parent2 = Key.newBuilder("ds", "kind3", "name").setNamespace("ns").build();
     IncompleteKey pk3 = IncompleteKey.newBuilder(parent2, "kind3").build();
     assertEquals(parent2, pk3.getParent());