Elasticsearch : failure in bulk execution

Question

I was able to index documents in bulk before I installed xpack. After installing xpack, I am getting failure in bulk execution: . I am using java client for xpack

<dependency>
        <groupId>org.elasticsearch.client</groupId>
        <artifactId>x-pack-transport</artifactId>
        <version>5.5.1</version>
 </dependency>

and connecting to ES server via

client = new PreBuiltXPackTransportClient(Settings.builder()
.put("cluster.name", "name")
.put("xpack.security.user", "user:pass")
.build())
.addTransportAddress(new InetSocketTransportAddress(InetAddress.getByName("ip"), 9300));

and bulk indexing

    try {
    BulkResponse r = bulkRequest.get();
   System.out.println("number of actions : 
   "+bulkRequest.numberOfActions()); // prints 29
    System.out.println(r.buildFailureMessage()); // prints failure in bulk 
     execution:
    for(BulkItemResponse a : r.getItems()){
    System.out.println("failure message : "+a.getFailureMessage()); //failure message : null
    System.out.println("response : "+a.getResponse()); // prints response : IndexResponse[index=bigmart_bill_store_id,type=bill_store_id,id=AWCWJzhqNaFB56dBfQnX,version=1,result=created,shards={"total":2,"successful":1,"failed":0}]
    System.out.println("failure : "+a.getFailure()); // prints failure message : null
    }
    new ConfigureES().client.close();
    } catch (Exception we) {
    we.printStackTrace();
    }

this code was working fine before installing xpack.Now it is giving me error.I don't get any exception or any error stack trace and I cannot bulk index
I will provide any information required to debug this error