diff --git a/java/com/google/gerrit/server/cache/h2/H2CacheImpl.java b/java/com/google/gerrit/server/cache/h2/H2CacheImpl.java
index 13b8b12..0403408 100644
--- a/java/com/google/gerrit/server/cache/h2/H2CacheImpl.java
+++ b/java/com/google/gerrit/server/cache/h2/H2CacheImpl.java
@@ -548,7 +548,7 @@
         c.touch = c.conn.prepareStatement("UPDATE data SET accessed=? WHERE k=? AND version=?");
       }
       try {
-        c.touch.setTimestamp(1, TimeUtil.nowTs());
+        c.touch.setTimestamp(1, new Timestamp(TimeUtil.nowMs()));
         keyType.set(c.touch, 2, key);
         c.touch.setInt(3, version);
         c.touch.executeUpdate();
@@ -581,7 +581,7 @@
           c.put.setBytes(2, valueSerializer.serialize(holder.value));
           c.put.setInt(3, version);
           c.put.setTimestamp(4, Timestamp.from(holder.created));
-          c.put.setTimestamp(5, TimeUtil.nowTs());
+          c.put.setTimestamp(5, new Timestamp(TimeUtil.nowMs()));
           c.put.executeUpdate();
           holder.clean = true;
         } finally {
diff --git a/java/com/google/gerrit/server/logging/RequestId.java b/java/com/google/gerrit/server/logging/RequestId.java
index 543f0a2..3ae9598 100644
--- a/java/com/google/gerrit/server/logging/RequestId.java
+++ b/java/com/google/gerrit/server/logging/RequestId.java
@@ -61,7 +61,7 @@
     h.putLong(Thread.currentThread().getId()).putUnencodedChars(MACHINE_ID);
     str =
         (resourceId != null ? resourceId + "-" : "")
-            + TimeUtil.nowTs().getTime()
+            + TimeUtil.now().toEpochMilli()
             + "-"
             + h.hash().toString().substring(0, 8);
   }
diff --git a/java/com/google/gerrit/server/util/time/TimeUtil.java b/java/com/google/gerrit/server/util/time/TimeUtil.java
index 34af97e..b455805 100644
--- a/java/com/google/gerrit/server/util/time/TimeUtil.java
+++ b/java/com/google/gerrit/server/util/time/TimeUtil.java
@@ -44,10 +44,6 @@
     return Instant.ofEpochMilli(nowMs());
   }
 
-  public static Timestamp nowTs() {
-    return new Timestamp(nowMs());
-  }
-
   /**
    * Returns the magic timestamp representing no specific time.
    *
@@ -59,10 +55,6 @@
     return new Timestamp(0);
   }
 
-  public static Timestamp truncateToSecond(Timestamp t) {
-    return new Timestamp((t.getTime() / 1000) * 1000);
-  }
-
   public static Instant truncateToSecond(Instant t) {
     return Instant.ofEpochMilli(t.getEpochSecond() * 1000);
   }
diff --git a/javatests/com/google/gerrit/acceptance/ProjectResetterTest.java b/javatests/com/google/gerrit/acceptance/ProjectResetterTest.java
index 7d04558..877ccd5 100644
--- a/javatests/com/google/gerrit/acceptance/ProjectResetterTest.java
+++ b/javatests/com/google/gerrit/acceptance/ProjectResetterTest.java
@@ -36,6 +36,7 @@
 import com.google.gerrit.testing.InMemoryRepositoryManager;
 import com.google.gerrit.testing.TestTimeUtil;
 import java.io.IOException;
+import java.util.Date;
 import java.util.concurrent.TimeUnit;
 import org.eclipse.jgit.lib.CommitBuilder;
 import org.eclipse.jgit.lib.Constants;
@@ -332,10 +333,13 @@
     assertThat(repo.exactRef(ref.getName())).isNull();
   }
 
+  // TODO(issue-15517): Fix the JdkObsolete issue with Date once JGit's PersonIdent class supports
+  // Instants
+  @SuppressWarnings("JdkObsolete")
   private ObjectId createCommit(Repository repo) throws IOException {
     try (ObjectInserter oi = repo.newObjectInserter()) {
       PersonIdent ident =
-          new PersonIdent(new PersonIdent("Foo Bar", "foo.bar@baz.com"), TimeUtil.nowTs());
+          new PersonIdent(new PersonIdent("Foo Bar", "foo.bar@baz.com"), Date.from(TimeUtil.now()));
       CommitBuilder cb = new CommitBuilder();
       cb.setTreeId(oi.insert(Constants.OBJ_TREE, new byte[] {}));
       cb.setCommitter(ident);
diff --git a/javatests/com/google/gerrit/acceptance/annotation/UseClockStepTest.java b/javatests/com/google/gerrit/acceptance/annotation/UseClockStepTest.java
index ecfe3f5..9d689ba 100644
--- a/javatests/com/google/gerrit/acceptance/annotation/UseClockStepTest.java
+++ b/javatests/com/google/gerrit/acceptance/annotation/UseClockStepTest.java
@@ -19,7 +19,6 @@
 import com.google.gerrit.acceptance.AbstractDaemonTest;
 import com.google.gerrit.acceptance.UseClockStep;
 import com.google.gerrit.server.util.time.TimeUtil;
-import java.sql.Timestamp;
 import java.time.Instant;
 import java.util.concurrent.TimeUnit;
 import org.junit.Test;
@@ -52,6 +51,6 @@
   @Test
   @UseClockStep(startAtEpoch = true)
   public void useClockStepWithStartAtEpoch() {
-    assertThat(TimeUtil.nowTs()).isEqualTo(Timestamp.from(Instant.EPOCH));
+    assertThat(TimeUtil.now()).isEqualTo(Instant.EPOCH);
   }
 }
diff --git a/javatests/com/google/gerrit/acceptance/api/accounts/AccountIT.java b/javatests/com/google/gerrit/acceptance/api/accounts/AccountIT.java
index 381bff6..3678e25 100644
--- a/javatests/com/google/gerrit/acceptance/api/accounts/AccountIT.java
+++ b/javatests/com/google/gerrit/acceptance/api/accounts/AccountIT.java
@@ -158,6 +158,7 @@
 import java.security.KeyPair;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Date;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Iterator;
@@ -2465,6 +2466,9 @@
   }
 
   @Test
+  // TODO(issue-15517): Fix the JdkObsolete issue with Date once JGit's PersonIdent class supports
+  // Instants
+  @SuppressWarnings("JdkObsolete")
   public void stalenessChecker() throws Exception {
     // Newly created account is not stale.
     AccountInfo accountInfo = gApi.accounts().create(name("foo")).get();
@@ -2478,7 +2482,7 @@
         RevWalk rw = new RevWalk(repo)) {
       RevCommit commit = rw.parseCommit(repo.exactRef(userRef).getObjectId());
 
-      PersonIdent ident = new PersonIdent(serverIdent.get(), TimeUtil.nowTs());
+      PersonIdent ident = new PersonIdent(serverIdent.get(), Date.from(TimeUtil.now()));
       CommitBuilder cb = new CommitBuilder();
       cb.setTreeId(commit.getTree());
       cb.setCommitter(ident);
diff --git a/javatests/com/google/gerrit/acceptance/api/group/GroupsIT.java b/javatests/com/google/gerrit/acceptance/api/group/GroupsIT.java
index 0c806b7..63b67f8 100644
--- a/javatests/com/google/gerrit/acceptance/api/group/GroupsIT.java
+++ b/javatests/com/google/gerrit/acceptance/api/group/GroupsIT.java
@@ -109,8 +109,10 @@
 import java.lang.annotation.Retention;
 import java.lang.annotation.Target;
 import java.sql.Timestamp;
+import java.time.Instant;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.Date;
 import java.util.List;
 import java.util.Map;
 import java.util.stream.Stream;
@@ -557,14 +559,17 @@
     assertThrows(AuthException.class, () -> gApi.groups().create(name("newGroup")));
   }
 
+  // TODO(issue-15508): Migrate timestamp fields in *Info/*Input classes from type Timestamp to
+  // Instant
+  @SuppressWarnings("JdkObsolete")
   @Test
   public void createdOnFieldIsPopulatedForNewGroup() throws Exception {
     // NoteDb allows only second precision.
-    Timestamp testStartTime = TimeUtil.truncateToSecond(TimeUtil.nowTs());
+    Instant testStartTime = TimeUtil.truncateToSecond(TimeUtil.now());
     String newGroupName = name("newGroup");
     GroupInfo group = gApi.groups().create(newGroupName).get();
 
-    assertThat(group.createdOn).isAtLeast(testStartTime);
+    assertThat(group.createdOn.toInstant()).isAtLeast(testStartTime);
   }
 
   @Test
@@ -1603,6 +1608,9 @@
     return createCommit(repo, commitMessage, null);
   }
 
+  // TODO(issue-15517): Fix the JdkObsolete issue with Date once JGit's PersonIdent class supports
+  // Instants
+  @SuppressWarnings("JdkObsolete")
   private ObjectId createCommit(Repository repo, String commitMessage, @Nullable ObjectId treeId)
       throws IOException {
     try (ObjectInserter oi = repo.newObjectInserter()) {
@@ -1610,7 +1618,7 @@
         treeId = oi.insert(Constants.OBJ_TREE, new byte[] {});
       }
 
-      PersonIdent ident = new PersonIdent(serverIdent.get(), TimeUtil.nowTs());
+      PersonIdent ident = new PersonIdent(serverIdent.get(), Date.from(TimeUtil.now()));
       CommitBuilder cb = new CommitBuilder();
       cb.setTreeId(treeId);
       cb.setCommitter(ident);
diff --git a/javatests/com/google/gerrit/acceptance/rest/change/AttentionSetIT.java b/javatests/com/google/gerrit/acceptance/rest/change/AttentionSetIT.java
index 9246442..b034a42 100644
--- a/javatests/com/google/gerrit/acceptance/rest/change/AttentionSetIT.java
+++ b/javatests/com/google/gerrit/acceptance/rest/change/AttentionSetIT.java
@@ -2049,7 +2049,7 @@
     comment.side = Side.REVISION;
     comment.path = Patch.COMMIT_MSG;
     comment.message = "comment";
-    comment.updated = TimeUtil.nowTs();
+    comment.setUpdated(TimeUtil.now());
     comment.inReplyTo = id;
     ReviewInput reviewInput = new ReviewInput();
     reviewInput.comments = ImmutableMap.of(Patch.COMMIT_MSG, ImmutableList.of(comment));
diff --git a/javatests/com/google/gerrit/server/git/DeleteZombieCommentsRefsTest.java b/javatests/com/google/gerrit/server/git/DeleteZombieCommentsRefsTest.java
index 3a8d7e4..29dbe58 100644
--- a/javatests/com/google/gerrit/server/git/DeleteZombieCommentsRefsTest.java
+++ b/javatests/com/google/gerrit/server/git/DeleteZombieCommentsRefsTest.java
@@ -29,6 +29,7 @@
 import com.google.gerrit.testing.InMemoryRepositoryManager;
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.Date;
 import java.util.List;
 import org.eclipse.jgit.lib.BatchRefUpdate;
 import org.eclipse.jgit.lib.CommitBuilder;
@@ -203,11 +204,14 @@
     return repo.exactRef(refName);
   }
 
+  // TODO(issue-15517): Fix the JdkObsolete issue with Date once JGit's PersonIdent class supports
+  // Instants
+  @SuppressWarnings("JdkObsolete")
   private static ObjectId createCommit(Repository repo, ObjectId treeId, ObjectId parentCommit)
       throws IOException {
     try (ObjectInserter oi = repo.newObjectInserter()) {
       PersonIdent committer =
-          new PersonIdent(new PersonIdent("Foo Bar", "foo.bar@baz.com"), TimeUtil.nowTs());
+          new PersonIdent(new PersonIdent("Foo Bar", "foo.bar@baz.com"), Date.from(TimeUtil.now()));
       CommitBuilder cb = new CommitBuilder();
       cb.setTreeId(treeId);
       cb.setCommitter(committer);
diff --git a/javatests/com/google/gerrit/server/git/meta/VersionedMetaDataTest.java b/javatests/com/google/gerrit/server/git/meta/VersionedMetaDataTest.java
index 690a5cc..6792703 100644
--- a/javatests/com/google/gerrit/server/git/meta/VersionedMetaDataTest.java
+++ b/javatests/com/google/gerrit/server/git/meta/VersionedMetaDataTest.java
@@ -30,6 +30,7 @@
 import com.google.gerrit.testing.TestTimeUtil;
 import java.io.IOException;
 import java.util.Arrays;
+import java.util.Date;
 import java.util.Optional;
 import java.util.TimeZone;
 import java.util.concurrent.TimeUnit;
@@ -220,9 +221,13 @@
     return u;
   }
 
+  // TODO(issue-15517): Fix the JdkObsolete issue with Date once JGit's PersonIdent class supports
+  // Instants
+  @SuppressWarnings("JdkObsolete")
   private CommitBuilder newCommitBuilder() {
     CommitBuilder cb = new CommitBuilder();
-    PersonIdent author = new PersonIdent("J. Author", "author@example.com", TimeUtil.nowTs(), TZ);
+    PersonIdent author =
+        new PersonIdent("J. Author", "author@example.com", Date.from(TimeUtil.now()), TZ);
     cb.setAuthor(author);
     cb.setCommitter(
         new PersonIdent(
diff --git a/javatests/com/google/gerrit/server/group/db/AbstractGroupTest.java b/javatests/com/google/gerrit/server/group/db/AbstractGroupTest.java
index abf0f0c..54407ca 100644
--- a/javatests/com/google/gerrit/server/group/db/AbstractGroupTest.java
+++ b/javatests/com/google/gerrit/server/group/db/AbstractGroupTest.java
@@ -31,6 +31,7 @@
 import com.google.gerrit.testing.InMemoryRepositoryManager;
 import java.io.IOException;
 import java.time.Instant;
+import java.util.Date;
 import java.util.Optional;
 import java.util.TimeZone;
 import org.eclipse.jgit.errors.ConfigInvalidException;
@@ -59,13 +60,16 @@
   protected Account.Id userId;
   protected PersonIdent userIdent;
 
+  // TODO(issue-15517): Fix the JdkObsolete issue with Date once JGit's PersonIdent class supports
+  // Instants
+  @SuppressWarnings("JdkObsolete")
   @Before
   public void abstractGroupTestSetUp() throws Exception {
     allUsersName = new AllUsersName(AllUsersNameProvider.DEFAULT);
     repoManager = new InMemoryRepositoryManager();
     allUsersRepo = repoManager.createRepository(allUsersName);
     serverAccountId = Account.id(SERVER_ACCOUNT_NUMBER);
-    serverIdent = new PersonIdent(SERVER_NAME, SERVER_EMAIL, TimeUtil.nowTs(), TZ);
+    serverIdent = new PersonIdent(SERVER_NAME, SERVER_EMAIL, Date.from(TimeUtil.now()), TZ);
     userId = Account.id(USER_ACCOUNT_NUMBER);
     userIdent = newPersonIdent(userId, serverIdent);
   }
@@ -112,8 +116,11 @@
     return md;
   }
 
+  // TODO(issue-15517): Fix the JdkObsolete issue with Date once JGit's PersonIdent class supports
+  // Instants
+  @SuppressWarnings("JdkObsolete")
   protected static PersonIdent newPersonIdent() {
-    return new PersonIdent(SERVER_NAME, SERVER_EMAIL, TimeUtil.nowTs(), TZ);
+    return new PersonIdent(SERVER_NAME, SERVER_EMAIL, Date.from(TimeUtil.now()), TZ);
   }
 
   protected static PersonIdent newPersonIdent(Account.Id id, PersonIdent ident) {
diff --git a/javatests/com/google/gerrit/server/group/db/GroupConfigTest.java b/javatests/com/google/gerrit/server/group/db/GroupConfigTest.java
index ddf35d6..dbe255c 100644
--- a/javatests/com/google/gerrit/server/group/db/GroupConfigTest.java
+++ b/javatests/com/google/gerrit/server/group/db/GroupConfigTest.java
@@ -1006,7 +1006,7 @@
   @Test
   public void commitTimeMatchesDefaultCreatedOnOfNewGroup() throws Exception {
     // Git timestamps are only precise to the second.
-    long testStartAsSecondsSinceEpoch = TimeUtil.nowTs().getTime() / 1000;
+    long testStartAsSecondsSinceEpoch = TimeUtil.now().getEpochSecond();
 
     InternalGroupCreation groupCreation =
         InternalGroupCreation.builder()
@@ -1117,7 +1117,7 @@
   @Test
   public void commitTimeMatchesDefaultUpdatedOnOfUpdatedGroup() throws Exception {
     // Git timestamps are only precise to the second.
-    long testStartAsSecondsSinceEpoch = TimeUtil.nowTs().getTime() / 1000;
+    long testStartAsSecondsSinceEpoch = TimeUtil.now().getEpochSecond();
 
     createArbitraryGroup(groupUuid);
     GroupDelta groupDelta =
@@ -1554,10 +1554,13 @@
     }
   }
 
+  // TODO(issue-15517): Fix the JdkObsolete issue with Date once JGit's PersonIdent class supports
+  // Instants
+  @SuppressWarnings("JdkObsolete")
   private MetaDataUpdate createMetaDataUpdate() {
     PersonIdent serverIdent =
         new PersonIdent(
-            "Gerrit Server", "noreply@gerritcodereview.com", TimeUtil.nowTs(), timeZone);
+            "Gerrit Server", "noreply@gerritcodereview.com", Date.from(TimeUtil.now()), timeZone);
 
     MetaDataUpdate metaDataUpdate =
         new MetaDataUpdate(
diff --git a/javatests/com/google/gerrit/server/group/db/GroupNameNotesTest.java b/javatests/com/google/gerrit/server/group/db/GroupNameNotesTest.java
index 3b7beb9..afc56ff 100644
--- a/javatests/com/google/gerrit/server/group/db/GroupNameNotesTest.java
+++ b/javatests/com/google/gerrit/server/group/db/GroupNameNotesTest.java
@@ -45,6 +45,7 @@
 import com.google.gerrit.truth.OptionalSubject;
 import java.io.IOException;
 import java.util.Arrays;
+import java.util.Date;
 import java.util.List;
 import java.util.Optional;
 import java.util.TimeZone;
@@ -557,8 +558,11 @@
     return GroupReference.create(AccountGroup.uuid(name + "-" + id), name);
   }
 
+  // TODO(issue-15517): Fix the JdkObsolete issue with Date once JGit's PersonIdent class supports
+  // Instants
+  @SuppressWarnings("JdkObsolete")
   private static PersonIdent newPersonIdent() {
-    return new PersonIdent(SERVER_NAME, SERVER_EMAIL, TimeUtil.nowTs(), TZ);
+    return new PersonIdent(SERVER_NAME, SERVER_EMAIL, Date.from(TimeUtil.now()), TZ);
   }
 
   private static ObjectId getNoteKey(GroupReference g) {
diff --git a/javatests/com/google/gerrit/server/notedb/AbstractChangeNotesTest.java b/javatests/com/google/gerrit/server/notedb/AbstractChangeNotesTest.java
index 53d3863..222be83 100644
--- a/javatests/com/google/gerrit/server/notedb/AbstractChangeNotesTest.java
+++ b/javatests/com/google/gerrit/server/notedb/AbstractChangeNotesTest.java
@@ -68,6 +68,7 @@
 import com.google.inject.Inject;
 import com.google.inject.Injector;
 import java.time.Instant;
+import java.util.Date;
 import java.util.TimeZone;
 import java.util.concurrent.ExecutorService;
 import org.eclipse.jgit.internal.storage.dfs.InMemoryRepository;
@@ -114,11 +115,15 @@
   protected Injector injector;
   private String systemTimeZone;
 
+  // TODO(issue-15517): Fix the JdkObsolete issue with Date once JGit's PersonIdent class supports
+  // Instants
+  @SuppressWarnings("JdkObsolete")
   @Before
   public void setUpTestEnvironment() throws Exception {
     setTimeForTesting();
 
-    serverIdent = new PersonIdent("Gerrit Server", "noreply@gerrit.com", TimeUtil.nowTs(), TZ);
+    serverIdent =
+        new PersonIdent("Gerrit Server", "noreply@gerrit.com", Date.from(TimeUtil.now()), TZ);
     project = Project.nameKey("test-project");
     repoManager = new InMemoryRepositoryManager();
     repo = repoManager.createRepository(project);
diff --git a/javatests/com/google/gerrit/server/notedb/CommitRewriterTest.java b/javatests/com/google/gerrit/server/notedb/CommitRewriterTest.java
index d858a5e..3b18183 100644
--- a/javatests/com/google/gerrit/server/notedb/CommitRewriterTest.java
+++ b/javatests/com/google/gerrit/server/notedb/CommitRewriterTest.java
@@ -47,9 +47,9 @@
 import com.google.gerrit.server.util.time.TimeUtil;
 import com.google.gson.Gson;
 import com.google.inject.Inject;
-import java.sql.Timestamp;
 import java.time.Instant;
 import java.util.Arrays;
+import java.util.Date;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
@@ -327,12 +327,12 @@
   @Test
   public void fixAuthorIdent() throws Exception {
     Change c = newChange();
-    Timestamp when = TimeUtil.nowTs();
+    Instant when = TimeUtil.now();
     PersonIdent invalidAuthorIdent =
         new PersonIdent(
             changeOwner.getName(),
             changeNoteUtil.getAccountIdAsEmailAddress(changeOwner.getAccountId()),
-            when,
+            Date.from(when),
             serverIdent.getTimeZone());
     RevCommit invalidUpdateCommit =
         writeUpdate(
@@ -932,6 +932,9 @@
     assertThat(secondRunResult.refsFailedToFix).isEmpty();
   }
 
+  // TODO(issue-15517): Fix the JdkObsolete issue with Date once JGit's PersonIdent class supports
+  // Instants
+  @SuppressWarnings("JdkObsolete")
   @Test
   public void fixRemoveVoteChangeMessageWithUnparsableAuthorIdent() throws Exception {
     Change c = newChange();
@@ -939,7 +942,7 @@
         new PersonIdent(
             changeOwner.getName(),
             "server@" + serverId,
-            TimeUtil.nowTs(),
+            Date.from(TimeUtil.now()),
             serverIdent.getTimeZone());
     writeUpdate(
         RefNames.changeMetaRef(c.getId()),
@@ -1566,6 +1569,9 @@
     assertThat(secondRunResult.refsFailedToFix).isEmpty();
   }
 
+  // TODO(issue-15517): Fix the JdkObsolete issue with Date once JGit's PersonIdent class supports
+  // Instants
+  @SuppressWarnings("JdkObsolete")
   @Test
   public void fixSubmitChangeMessageAndFooters() throws Exception {
     Change c = newChange();
@@ -1573,7 +1579,7 @@
         new PersonIdent(
             changeOwner.getName(),
             changeNoteUtil.getAccountIdAsEmailAddress(changeOwner.getAccountId()),
-            TimeUtil.nowTs(),
+            Date.from(TimeUtil.now()),
             serverIdent.getTimeZone());
     String changeOwnerIdentToFix = getAccountIdentToFix(changeOwner.getAccount());
     writeUpdate(
@@ -2275,16 +2281,19 @@
     assertThat(secondRunResult.refsFailedToFix).isEmpty();
   }
 
+  // TODO(issue-15517): Fix the JdkObsolete issue with Date once JGit's PersonIdent class supports
+  // Instants
+  @SuppressWarnings("JdkObsolete")
   @Test
   public void singleRunFixesAll() throws Exception {
     Change c = newChange();
-    Timestamp when = TimeUtil.nowTs();
+    Instant when = TimeUtil.now();
     String assigneeIdentToFix = getAccountIdentToFix(otherUser.getAccount());
     PersonIdent authorIdentToFix =
         new PersonIdent(
             changeOwner.getName(),
             changeNoteUtil.getAccountIdAsEmailAddress(changeOwner.getAccountId()),
-            when,
+            Date.from(when),
             serverIdent.getTimeZone());
 
     RevCommit invalidUpdateCommit =
diff --git a/javatests/com/google/gerrit/server/patch/DiffOperationsTest.java b/javatests/com/google/gerrit/server/patch/DiffOperationsTest.java
index 5a8b266..9f0fc29 100644
--- a/javatests/com/google/gerrit/server/patch/DiffOperationsTest.java
+++ b/javatests/com/google/gerrit/server/patch/DiffOperationsTest.java
@@ -32,6 +32,7 @@
 import com.google.inject.Inject;
 import com.google.inject.Injector;
 import java.io.IOException;
+import java.util.Date;
 import java.util.Map;
 import java.util.Optional;
 import org.eclipse.jgit.lib.CommitBuilder;
@@ -256,11 +257,14 @@
         : createCommitInRepo(repo, treeId, parentCommit);
   }
 
+  // TODO(issue-15517): Fix the JdkObsolete issue with Date once JGit's PersonIdent class supports
+  // Instants
+  @SuppressWarnings("JdkObsolete")
   private static ObjectId createCommitInRepo(Repository repo, ObjectId treeId, ObjectId... parents)
       throws IOException {
     try (ObjectInserter oi = repo.newObjectInserter()) {
       PersonIdent committer =
-          new PersonIdent(new PersonIdent("Foo Bar", "foo.bar@baz.com"), TimeUtil.nowTs());
+          new PersonIdent(new PersonIdent("Foo Bar", "foo.bar@baz.com"), Date.from(TimeUtil.now()));
       CommitBuilder cb = new CommitBuilder();
       cb.setTreeId(treeId);
       cb.setCommitter(committer);
diff --git a/javatests/com/google/gerrit/server/query/change/AbstractQueryChangesTest.java b/javatests/com/google/gerrit/server/query/change/AbstractQueryChangesTest.java
index bc0861c..55340e3 100644
--- a/javatests/com/google/gerrit/server/query/change/AbstractQueryChangesTest.java
+++ b/javatests/com/google/gerrit/server/query/change/AbstractQueryChangesTest.java
@@ -142,6 +142,7 @@
 import com.google.inject.Provider;
 import java.io.IOException;
 import java.sql.Timestamp;
+import java.time.Instant;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
@@ -1781,8 +1782,9 @@
     resetTimeWithClockStep(thirtyHoursInMs, MILLISECONDS);
     TestRepository<Repo> repo = createProject("repo");
     long startMs = TestTimeUtil.START.toEpochMilli();
-    Change change1 = insert(repo, newChange(repo), null, new Timestamp(startMs));
-    Change change2 = insert(repo, newChange(repo), null, new Timestamp(startMs + thirtyHoursInMs));
+    Change change1 = insert(repo, newChange(repo), null, Instant.ofEpochMilli(startMs));
+    Change change2 =
+        insert(repo, newChange(repo), null, Instant.ofEpochMilli(startMs + thirtyHoursInMs));
 
     // Stop time so age queries use the same endpoint.
     TestTimeUtil.setClockStep(0, MILLISECONDS);
@@ -1821,8 +1823,9 @@
     resetTimeWithClockStep(thirtyHoursInMs, MILLISECONDS);
     TestRepository<Repo> repo = createProject("repo");
     long startMs = TestTimeUtil.START.toEpochMilli();
-    Change change1 = insert(repo, newChange(repo), null, new Timestamp(startMs));
-    Change change2 = insert(repo, newChange(repo), null, new Timestamp(startMs + thirtyHoursInMs));
+    Change change1 = insert(repo, newChange(repo), null, Instant.ofEpochMilli(startMs));
+    Change change2 =
+        insert(repo, newChange(repo), null, Instant.ofEpochMilli(startMs + thirtyHoursInMs));
     TestTimeUtil.setClockStep(0, MILLISECONDS);
 
     // Change1 was last updated on 2009-09-30 21:00:00 -0000
@@ -1872,8 +1875,9 @@
     resetTimeWithClockStep(thirtyHoursInMs, MILLISECONDS);
     TestRepository<Repo> repo = createProject("repo");
     long startMs = TestTimeUtil.START.toEpochMilli();
-    Change change1 = insert(repo, newChange(repo), null, new Timestamp(startMs));
-    Change change2 = insert(repo, newChange(repo), null, new Timestamp(startMs + thirtyHoursInMs));
+    Change change1 = insert(repo, newChange(repo), null, Instant.ofEpochMilli(startMs));
+    Change change2 =
+        insert(repo, newChange(repo), null, Instant.ofEpochMilli(startMs + thirtyHoursInMs));
     TestTimeUtil.setClockStep(0, MILLISECONDS);
 
     // Change1 was last updated on 2009-09-30 21:00:00 -0000
@@ -4149,25 +4153,22 @@
   }
 
   protected Change insert(TestRepository<Repo> repo, ChangeInserter ins) throws Exception {
-    return insert(repo, ins, null, TimeUtil.nowTs());
+    return insert(repo, ins, null, TimeUtil.now());
   }
 
   protected Change insert(TestRepository<Repo> repo, ChangeInserter ins, @Nullable Account.Id owner)
       throws Exception {
-    return insert(repo, ins, owner, TimeUtil.nowTs());
+    return insert(repo, ins, owner, TimeUtil.now());
   }
 
   protected Change insert(
-      TestRepository<Repo> repo,
-      ChangeInserter ins,
-      @Nullable Account.Id owner,
-      Timestamp createdOn)
+      TestRepository<Repo> repo, ChangeInserter ins, @Nullable Account.Id owner, Instant createdOn)
       throws Exception {
     Project.NameKey project =
         Project.nameKey(repo.getRepository().getDescription().getRepositoryName());
     Account.Id ownerId = owner != null ? owner : userId;
     IdentifiedUser user = userFactory.create(ownerId);
-    try (BatchUpdate bu = updateFactory.create(project, user, createdOn.toInstant())) {
+    try (BatchUpdate bu = updateFactory.create(project, user, createdOn)) {
       bu.insertChange(ins);
       bu.execute();
       return ins.getChange();