Fix NullPointerException when evaluating draft reviews

This change in Gerrit introduced a bug for draft reviews:
https://gerrit-review.googlesource.com/#/c/67762/3/gerrit-server/src/main/java/com/google/gerrit/server/project/SubmitRuleEvaluator.java
An NPE is thrown when the patchSet is not set before calling
SubmitRuleEvaluator#evaluate().  This fix is a workaround until Gerrit
is fixed.

Change-Id: If531822421d501bd7970e03754d5ae5d8f3654ae

src/main/java/com/criteo/gerrit/plugins/automerge/AtomicityHelper.java

diff --git a/src/main/java/com/criteo/gerrit/plugins/automerge/AtomicityHelper.java b/src/main/java/com/criteo/gerrit/plugins/automerge/AtomicityHelper.java
index b910113..e65d35e 100644
--- a/src/main/java/com/criteo/gerrit/plugins/automerge/AtomicityHelper.java
+++ b/src/main/java/com/criteo/gerrit/plugins/automerge/AtomicityHelper.java
@@ -108,7 +108,8 @@
    */
   public boolean isSubmittable(final int change) throws OrmException {
     final ChangeData changeData = changeDataFactory.create(db.get(), new Change.Id(change));
-    final List<SubmitRecord> cansubmit = new SubmitRuleEvaluator(changeData).evaluate();
+    // For draft reviews, the patchSet must be set to avoid an NPE.
+    final List<SubmitRecord> cansubmit = new SubmitRuleEvaluator(changeData).setPatchSet(changeData.currentPatchSet()).evaluate();
     log.debug(String.format("Checking if change %d is submitable.", change));
     for (final SubmitRecord submit : cansubmit) {
       if (submit.status != SubmitRecord.Status.OK) {