springboot elasticsearch7.5 + springboot 2.2.2.release elasticsearchRepository.save date err

elasticsearch version is 7.3 and spring-boot-starter-data-elasticsearch version is 2.2.2.release

this is my model

    @Field(type = FieldType.Date ,store = true, format = DateFormat.custom, pattern = "yyyy-MM-dd'T'hh:mm:ss.SSS'Z'")
    @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'")
    @JsonProperty(value = "createtime")
    private Date ctime;    

    private String name;

and when i try to insert data

        Label label = new Label();
        label.setCtime(new Date());
        label.setName("admin");
        LabelRepository.save(label);

I can successfully insert the data, but when I look at the data, no createtime in the document

    "hits": [
      {
        "_index": "label",
        "_type": "_doc",
        "_id": "3fc7e940f25843d4886b85e0461bc9d7",
        "_score": 3.3787246,
        "_source": {
          "name":"admin"
        }
      }
    ]

index mapping

        "createTime": {
          "type": "date",
          "store": true,
          "format": "yyyy-MM-dd'T'hh:mm:ss.SSS'Z'"
        }

but it was ok when elasticsearch6.8 + springboot 2.0.4

what should i do ?

Comment From: snicoll

@coldwarm7 please ask your question on StackOverflow or on the Elasticserach forum for help on upgrading to ES 7.5.