[es/snapshot.restore] Missing required property 'RestoreResponse.snapshot' with wait_for_completion=false

[synox]

Java API client version

7.16.2 and 7.17.1

Java version

java 11.0.14 2022-01-18 LTS

Elasticsearch Version

7.16.2

Problem description

Running snapshot restore with wait_for_completion=false does not work with the Java client.

Call:

            client
                    .snapshot()
                    .restore(r -> r
                                    .repository(snapshotRepositoryName)
                                    .snapshot(snapshotName)
                                    .indices(globPatterns)
                                    .renamePattern(renamePattern.getSearchRegex())
                                    .renameReplacement(renamePattern.getReplacementRegex())
                                    .includeAliases(false)
                                    .waitForCompletion(false)

Results in URI:

/_snapshot/myRepoName/cloud-snapshot-2022.02.23-asdf/_restore?wait_for_completion=false

Error:

co.elastic.clients.util.MissingRequiredPropertyException: Missing required property 'RestoreResponse.snapshot'

	at co.elastic.clients.util.ApiTypeHelper.requireNonNull(ApiTypeHelper.java:76)
	at co.elastic.clients.elasticsearch.snapshot.RestoreResponse.<init>(RestoreResponse.java:57)
	at co.elastic.clients.elasticsearch.snapshot.RestoreResponse.<init>(RestoreResponse.java:50)
	at co.elastic.clients.elasticsearch.snapshot.RestoreResponse$Builder.build(RestoreResponse.java:121)
	at co.elastic.clients.elasticsearch.snapshot.RestoreResponse$Builder.build(RestoreResponse.java:94)
	at co.elastic.clients.json.ObjectBuilderDeserializer.deserialize(ObjectBuilderDeserializer.java:80)
	at co.elastic.clients.json.DelegatingDeserializer$SameType.deserialize(DelegatingDeserializer.java:43)
	at co.elastic.clients.transport.rest_client.RestClientTransport.decodeResponse(RestClientTransport.java:325)
	at co.elastic.clients.transport.rest_client.RestClientTransport.getHighLevelResponse(RestClientTransport.java:291)
	at co.elastic.clients.transport.rest_client.RestClientTransport.performRequest(RestClientTransport.java:144)
	at co.elastic.clients.elasticsearch.snapshot.ElasticsearchSnapshotClient.restore(ElasticsearchSnapshotClient.java:361)
	at co.elastic.clients.elasticsearch.snapshot.ElasticsearchSnapshotClient.restore(ElasticsearchSnapshotClient.java:377)

The same problem also happens with es/snapshot.restore:

co.elastic.clients.util.MissingRequiredPropertyException: Missing required property 'CreateSnapshotResponse.snapshot'

	at co.elastic.clients.util.ApiTypeHelper.requireNonNull(ApiTypeHelper.java:76)
	at co.elastic.clients.elasticsearch.snapshot.CreateSnapshotResponse.<init>(CreateSnapshotResponse.java:61)
	at co.elastic.clients.elasticsearch.snapshot.CreateSnapshotResponse.<init>(CreateSnapshotResponse.java:50)

Notes

From what I understand, the server responds with {"acknowledged":true} but in the spec the "snapshot" is mandatory.
https://github.com/elastic/elasticsearch-specification/blob/d19af7a3ccd53459593246fbc2fffe0c33d86712/specification/snapshot/restore/SnapshotRestoreResponse.ts#L24

See similar PR: https://github.com/elastic/elasticsearch-specification/pull/1326/files

[synox]

cc: @fabriziofortino

[swallez]

The current definition of this type indeed doesn't take into account wait_for_completion=false and expects snapshot information to be present in the response body.

Rather than just making this property optional, we need do define a better solution to correctly handle all the API endpoints that accept a wait_for_completion parameter. I opened elastic/elasticsearch-specification#1767 to address this at the API specification level, which will then be implemented in the Java API client.