@Override
 public void onPreMerge(
     Repository repo,
     CodeReviewCommit commit,
     ProjectState destProject,
     Branch.NameKey destBranch,
     PatchSet.Id patchSetId)
     throws MergeValidationException {
   for (MergeValidationListener validator : mergeValidationListeners) {
     validator.onPreMerge(repo, commit, destProject, destBranch, patchSetId);
   }
 }
  public void validatePreMerge(
      Repository repo,
      CodeReviewCommit commit,
      ProjectState destProject,
      Branch.NameKey destBranch,
      PatchSet.Id patchSetId)
      throws MergeValidationException {
    List<MergeValidationListener> validators = Lists.newLinkedList();

    validators.add(new PluginMergeValidationListener(mergeValidationListeners));
    validators.add(projectConfigValidatorFactory.create());

    for (MergeValidationListener validator : validators) {
      validator.onPreMerge(repo, commit, destProject, destBranch, patchSetId);
    }
  }