Adapt to change in Gerrit core

Change Id93e378be changed the signature of
MergeValidationListener#onPreMerge.

Signed-off-by: Edwin Kempin <ekempin@google.com>
Change-Id: I8f379e16eead07074f7f2f9c989a2e587c83383c

src/main/java/com/googlesource/gerrit/plugins/hooks/Submit.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/hooks/Submit.java b/src/main/java/com/googlesource/gerrit/plugins/hooks/Submit.java
index 1358d0a..0666fcf 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/hooks/Submit.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/hooks/Submit.java
@@ -18,6 +18,7 @@
 import com.google.gerrit.entities.PatchSet;
 import com.google.gerrit.server.IdentifiedUser;
 import com.google.gerrit.server.git.CodeReviewCommit;
+import com.google.gerrit.server.git.CodeReviewCommit.CodeReviewRevWalk;
 import com.google.gerrit.server.git.validators.MergeValidationException;
 import com.google.gerrit.server.git.validators.MergeValidationListener;
 import com.google.gerrit.server.project.ProjectState;
@@ -39,6 +40,7 @@
   @Override
   public void onPreMerge(
       Repository repo,
+      CodeReviewRevWalk revWalk,
       CodeReviewCommit commit,
       ProjectState destProject,
       BranchNameKey destBranch,