如何在桶聚合后将桶内元素进行拼接并作为一个新的字段

查询语句如下:

{

	"size": 0,

	"query": {

		"bool": {

			"should": [

				{

					"match": {

						"title": "异动信息 行文时间"

					}

				},

				{

					"match": {

						"value": "异动信息 行文时间"

					}

				}

			]

		}

	},

	"aggs": {

		"linkId_group": {

			"terms": {

				"field": "linkId.keyword",

				"size": 5

			},

			"aggs": {

				"bucket_data": {

					"top_hits": {

						"_source": {

							"includes": [

								"title",

								"value",

								"linkId"

							]

						},

						"size": 2

					}

				}

			}

		}

	}

}

聚合结果如下:

{

	"took": 129,

	"timed_out": false,

	"_shards": {

		"total": 1,

		"successful": 1,

		"skipped": 0,

		"failed": 0

	},

	"hits": {

		"total": {

			"value": 10000,

			"relation": "gte"

		},

		"max_score": null,

		"hits": []

	},

	"aggregations": {

		"linkId_group": {

			"doc_count_error_upper_bound": 0,

			"sum_other_doc_count": 334033,

			"buckets": [

				{

					"key": "1304729b27483fc3991a6ab24552301c",

					"doc_count": 236,

					"bucket_data": {

						"hits": {

							"total": {

								"value": 236,

								"relation": "eq"

							},

							"max_score": 20.774427,

							"hits": [

								{

									"_index": "unified-search-a",

									"_type": "_doc",

									"_id": "wLWeZIQBGLSYSXqsPCne",

									"_score": 20.774427,

									"_source": {

										"linkId": "1304729b27483fc3991a6ab24552301c",

										"title": "学生信息 学籍异动信息",

										"value": "行文时间: 2016-10-12"

									}

								},

								{

									"_index": "unified-search-a",

									"_type": "_doc",

									"_id": "jLWeZIQBGLSYSXqsPFDo",

									"_score": 20.774427,

									"_source": {

										"linkId": "1304729b27483fc3991a6ab24552301c",

										"title": "学生信息 学籍异动信息",

										"value": "行文时间: 2018-05-21"

									}

								}

							]

						}

					}

				},

				{

					"key": "744c73954c5e3c778b8c96dd1b1bb009",

					"doc_count": 233,

					"bucket_data": {

						"hits": {

							"total": {

								"value": 233,

								"relation": "eq"

							},

							"max_score": 20.774427,

							"hits": [

								{

									"_index": "unified-search-a",

									"_type": "_doc",

									"_id": "ZbKXZIQBGLSYSXqs25oC",

									"_score": 20.774427,

									"_source": {

										"linkId": "744c73954c5e3c778b8c96dd1b1bb009",

										"title": "学生信息 学籍异动信息",

										"value": "行文时间: 2017-02-21"

									}

								},

								{

									"_index": "unified-search-a",

									"_type": "_doc",

									"_id": "BrKXZIQBGLSYSXqs25wD",

									"_score": 20.774427,

									"_source": {

										"linkId": "744c73954c5e3c778b8c96dd1b1bb009",

										"title": "学生信息 学籍异动信息",

										"value": "行文时间: 2017-06-02"

									}

								}

							]

						}

					}

				},

				{

					"key": "f6805fb3d99f391bb0f43b6bb45d120b",

					"doc_count": 232,

					"bucket_data": {

						"hits": {

							"total": {

								"value": 232,

								"relation": "eq"

							},

							"max_score": 20.774427,

							"hits": [

								{

									"_index": "unified-search-a",

									"_type": "_doc",

									"_id": "FLahZIQBGLSYSXqsaG3E",

									"_score": 20.774427,

									"_source": {

										"linkId": "f6805fb3d99f391bb0f43b6bb45d120b",

										"title": "学生信息 学籍异动信息",

										"value": "行文时间: 2017-03-06"

									}

								},

								{

									"_index": "unified-search-a",

									"_type": "_doc",

									"_id": "crahZIQBGLSYSXqsaG3E",

									"_score": 20.774427,

									"_source": {

										"linkId": "f6805fb3d99f391bb0f43b6bb45d120b",

										"title": "学生信息 学籍异动信息",

										"value": "行文时间: 2017-09-28"

									}

								}

							]

						}

					}

				},

				{

					"key": "bf02e128126b30d0ae1d1be222199f96",

					"doc_count": 192,

					"bucket_data": {

						"hits": {

							"total": {

								"value": 192,

								"relation": "eq"

							},

							"max_score": 20.774427,

							"hits": [

								{

									"_index": "unified-search-a",

									"_type": "_doc",

									"_id": "crKXZIQBGLSYSXqs26EE",

									"_score": 20.774427,

									"_source": {

										"linkId": "bf02e128126b30d0ae1d1be222199f96",

										"title": "学生信息 学籍异动信息",

										"value": "行文时间: 2018-10-19"

									}

								},

								{

									"_index": "unified-search-a",

									"_type": "_doc",

									"_id": "XLKXZIQBGLSYSXqs26IE",

									"_score": 20.774427,

									"_source": {

										"linkId": "bf02e128126b30d0ae1d1be222199f96",

										"title": "学生信息 学籍异动信息",

										"value": "行文时间: 2019-10-10"

									}

								}

							]

						}

					}

				},

				{

					"key": "ecbbd847e29c3f7ab45440b062c6b7c2",

					"doc_count": 189,

					"bucket_data": {

						"hits": {

							"total": {

								"value": 189,

								"relation": "eq"

							},

							"max_score": 20.774427,

							"hits": [

								{

									"_index": "unified-search-a",

									"_type": "_doc",

									"_id": "k7qwZIQBGLSYSXqsBY45",

									"_score": 20.774427,

									"_source": {

										"linkId": "ecbbd847e29c3f7ab45440b062c6b7c2",

										"title": "学生信息 学籍异动信息",

										"value": "行文时间: 2018-11-29"

									}

								},

								{

									"_index": "unified-search-a",

									"_type": "_doc",

									"_id": "O7qwZIQBGLSYSXqsBZA6",

									"_score": 20.774427,

									"_source": {

										"linkId": "ecbbd847e29c3f7ab45440b062c6b7c2",

										"title": "学生信息 学籍异动信息",

										"value": "行文时间: 2019-03-06"

									}

								}

							]

						}

					}

				}

			]

		}

	}

}

现在我想把每个 bucket 中的数据拼接起来作为一个新的字段，如拼接 "_source" 中的  "value" 字段，拼接后为 "行文时间: 2019-03-06 行文时间: 2019-03-06"，有什么办法能做到吗