#vulnerable code 
                                @Override
    protected SuggestRefreshResponse newResponse(SuggestRefreshRequest request, AtomicReferenceArray shardsResponses, ClusterState clusterState) {
        int successfulShards = 0;
        int failedShards = 0;
        List<ShardOperationFailedException> shardFailures = null;

        for (int i = 0; i < shardsResponses.length(); i++) {
            Object shardResponse = shardsResponses.get(i);
            if (shardResponse == null) {
                failedShards++;
            } else if (shardResponse instanceof BroadcastShardOperationFailedException) {
                failedShards++;
                shardFailures.add(new DefaultShardOperationFailedException((BroadcastShardOperationFailedException) shardResponse));
            } else {
                successfulShards++;
            }
        }

        return new SuggestRefreshResponse(shardsResponses.length(), successfulShards, failedShards, shardFailures);
    } 
                            #location 13 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                @Override
    protected SuggestRefreshResponse newResponse(SuggestRefreshRequest request, AtomicReferenceArray shardsResponses, ClusterState clusterState) {
        int successfulShards = 0;
        int failedShards = 0;
        List<ShardOperationFailedException> shardFailures = Lists.newArrayList();

        for (int i = 0; i < shardsResponses.length(); i++) {
            Object shardResponse = shardsResponses.get(i);
            if (shardResponse == null) {
                failedShards++;
            } else if (shardResponse instanceof BroadcastShardOperationFailedException) {
                failedShards++;
                shardFailures.add(new DefaultShardOperationFailedException((BroadcastShardOperationFailedException) shardResponse));
            } else {
                successfulShards++;
            }
        }

        return new SuggestRefreshResponse(shardsResponses.length(), successfulShards, failedShards, shardFailures);
    }