Merge branch 'stable-2.15'

* stable-2.15:
  PropertyExtractor: Add null check for event.submitter

Change-Id: I32fdab3192501e964eeb0008269fca9e9383abeb

src/main/java/com/googlesource/gerrit/plugins/its/base/util/PropertyExtractor.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/its/base/util/PropertyExtractor.java b/src/main/java/com/googlesource/gerrit/plugins/its/base/util/PropertyExtractor.java
index a969b4c..6cc93da 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/its/base/util/PropertyExtractor.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/its/base/util/PropertyExtractor.java
@@ -103,7 +103,9 @@
 
   private Map<String, Set<String>> extractFrom(RefUpdatedEvent event, Set<Property> common) {
     common.add(propertyFactory.create("event-type", event.type));
-    common.addAll(propertyAttributeExtractor.extractFrom(event.submitter.get(), "submitter"));
+    if (event.submitter != null) {
+      common.addAll(propertyAttributeExtractor.extractFrom(event.submitter.get(), "submitter"));
+    }
     common.addAll(propertyAttributeExtractor.extractFrom(event.refUpdate.get()));
     RefUpdateAttribute refUpdated = event.refUpdate.get();
     if (ObjectId.zeroId().name().equals(refUpdated.newRev)) {