Use a more readable assertion style when comparing Timestamps

Change-Id: I87c7c1a930fbf23fa48322d3802ecc218c202581

src/test/java/com/googlesource/gerrit/plugins/spannerrefdb/LockTest.java

diff --git a/src/test/java/com/googlesource/gerrit/plugins/spannerrefdb/LockTest.java b/src/test/java/com/googlesource/gerrit/plugins/spannerrefdb/LockTest.java
index 988b32b..e8beaa8 100644
--- a/src/test/java/com/googlesource/gerrit/plugins/spannerrefdb/LockTest.java
+++ b/src/test/java/com/googlesource/gerrit/plugins/spannerrefdb/LockTest.java
@@ -105,7 +105,7 @@
     try (AutoCloseable refLock = refDb.lockRef(PROJECT_NAME_KEY, REF_NAME)) {
       Timestamp newLockToken = getLockTimestamp(PROJECT_NAME_KEY, REF_NAME, TOKEN);
       assertThat(newLockToken).isNotNull();
-      assertThat(staleTimestamp.compareTo(newLockToken)).isLessThan(0);
+      assertThat(staleTimestamp).isLessThan(newLockToken);
     }
   }