ChangeJson: Fix NullPointerException when cd.currentPatchSet() is null

Change Ib7b4f378b added a log statement to log cases where the current
patch set in cd.change().currentPatchSetId() mismatches
cd.currentPatchSet(). One of the cases where there is a mismatch is when
cd.change().currentPatchSetId() returns a patch set ID, but
cd.currentPatchSet() returns null.

Release-Notes: skip
Change-Id: Ibd7a4eb1cca27f87e5bf84e8072d1d3bb4c65cd9
Signed-off-by: Edwin Kempin <ekempin@google.com>
(cherry picked from commit 63e041bc3abb7d298d24cdce1aff0300bd0c5976)

1 files changed, 4 insertions, 2 deletions

diff --git a/java/com/google/gerrit/server/change/ChangeJson.java b/java/com/google/gerrit/server/change/ChangeJson.java
index 2b7f8facf7..1a8d48c548 100644
--- a/java/com/google/gerrit/server/change/ChangeJson.java
+++ b/java/com/google/gerrit/server/change/ChangeJson.java
@@ -780,10 +780,12 @@ public class ChangeJson {
                 .filter(refState -> PatchSet.Id.fromRef(refState.ref()) != null)
                 .map(refState -> refState.ref() + ":" + refState.id().name())
                 .collect(toList()));
-        if (!cd.change().currentPatchSetId().equals(cd.currentPatchSet().id())) {
+        PatchSet.Id currentPatchSetFromChangeData =
+            Optional.ofNullable(cd.currentPatchSet()).map(PatchSet::id).orElse(null);
+        if (!cd.change().currentPatchSetId().equals(currentPatchSetFromChangeData)) {
           logger.atSevere().log(
               "mismatch between current patch set in Change (%s) and ChangeData (%s)",
-              cd.change().currentPatchSetId(), cd.currentPatchSet().id());
+              cd.change().currentPatchSetId(), currentPatchSetFromChangeData);
         }
       }
     }