Add ml.get_transform_stats issues in response

[pquentin]

This is a field that we have missed until now even though it was documented, except for type which was added in 8.8. It appeared in this YAML test today.

Regarding server code:

• issues is added in TransformHealth.toXContent
• issues is written in TransformHealthIssue.toXContent

[github-actions]

Following you can find the validation results for the API you have changed.

API	Status	Request	Response
transform.get_transform_stats	🟢	34/34	34/34

You can validate this API yourself by using the make validate target.

[l-trotta]

around the spec I saw various instance where we also map the human readable field, so both first_occurrence and first_occurrence_string

[pquentin]

Done. We can indeed get this when passing ?human, here are samples outputs for get_transform

{
  "count": 1,
  "transforms": [
    {
      "id": "test",
      "authorization": {
        "roles": [
          "superuser"
        ]
      },
      "version": "10.0.0",
      "create_time_string": "2025-03-26T11:25:45.642Z",
      "create_time": 1742988345642,
      "source": {
        "index": [
          "kibana_sample_data_ecommerce"
        ],
        "query": {
          "match_all": {}
        }
      },
      "dest": {
        "index": "test"
      },
      "pivot": {
        "group_by": {
          "category": {
            "terms": {
              "field": "category.keyword"
            }
          }
        },
        "aggregations": {
          "customer_id.cardinality": {
            "cardinality": {
              "field": "customer_id"
            }
          }
        }
      },
      "settings": {}
    }
  ]
}

and get_transform_stats:

{
  "count": 1,
  "transforms": [
    {
      "id": "test",
      "state": "stopped",
      "stats": {
        "pages_processed": 2,
        "documents_processed": 7409,
        "documents_indexed": 6,
        "documents_deleted": 0,
        "trigger_count": 1,
        "index_time_in_ms": 2,
        "index_total": 1,
        "index_failures": 0,
        "search_time_in_ms": 3,
        "search_total": 2,
        "search_failures": 0,
        "processing_time_in_ms": 0,
        "processing_total": 2,
        "delete_time_in_ms": 0,
        "exponential_avg_checkpoint_duration_ms": 19,
        "exponential_avg_documents_indexed": 6,
        "exponential_avg_documents_processed": 7409
      },
      "checkpointing": {
        "last": {
          "checkpoint": 1,
          "timestamp": "2025-03-26T11:25:46.849Z",
          "timestamp_millis": 1742988346849
        },
        "changes_last_detected_at_string": "2025-03-26T11:25:46.849Z",
        "changes_last_detected_at": 1742988346849
      },
      "health": {
        "status": "green"
      }
    }
  ]
}

I fixed the ones I saw here.

[github-actions]

Following you can find the validation results for the APIs you have changed.

API	Status	Request	Response
transform.get_transform_stats	🟢	34/34	34/34
transform.get_transform	🟢	26/26	26/26

You can validate these APIs yourself by using the make validate target.

[pquentin]

Defined in https://github.com/elastic/elasticsearch/blob/6503c1b94bf077a9fc152019932a79c4e4f42d40/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/transform/transforms/TransformCheckpointingInfo.java#L209-L230