Fix _type deprecation on simulate pipeline API (#116259)

A change in 8.0.0 was intended to deprecate specifying `_type` in a
document passed to the simulate pipeline API, unless it was in BWC
mode for v7. There was a logic error which meant that the warning
would actually *only* fire in BWC mode... except that the API version
was not being correctly passed from the REST request to the transport
request, so the warning would never fire.

This change for the 9.0 release fixes both issues, so that the
deprecation warning fires unless it is in BWC mode for v8.

Author: PeteGillinElastic

docs/changelog/116259.yaml

@@ -0,0 +1,14 @@
+pr: 116259
+summary: Fix `_type` deprecation on simulate pipeline API
+area: Ingest Node
+type: deprecation
+issues: []
+deprecation:
+  title: Document `_type` deprecated on simulate pipeline API
+  area: REST API
+  details: >-
+    Passing a document with a `_type` property is deprecated in the `/_ingest/pipeline/{id}/_simulate` and
+    `/_ingest/pipeline/_simulate` APIs.
+  impact: >-
+    Users should already have stopped using mapping types, which were deprecated in {es} 7. This deprecation warning
+    will fire if they specify mapping types on documents pass to the simulate pipeline API.

server/src/main/java/org/elasticsearch/action/ingest/SimulatePipelineRequest.java

@@ -18,6 +18,7 @@
 import org.elasticsearch.common.lucene.uid.Versions;
 import org.elasticsearch.common.xcontent.XContentHelper;
 import org.elasticsearch.core.RestApiVersion;
+import org.elasticsearch.core.UpdateForV10;
 import org.elasticsearch.index.VersionType;
 import org.elasticsearch.ingest.ConfigurationUtils;
 import org.elasticsearch.ingest.IngestDocument;
@@ -156,6 +157,7 @@ static Parsed parse(Map<String, Object> config, boolean verbose, IngestService i
         return new Parsed(pipeline, ingestDocumentList, verbose);
     }
 
+    @UpdateForV10(owner = UpdateForV10.Owner.DATA_MANAGEMENT) // Unconditionally deprecate the _type field once V8 BWC support is removed
     private static List<IngestDocument> parseDocs(Map<String, Object> config, RestApiVersion restApiVersion) {
         List<Map<String, Object>> docs = ConfigurationUtils.readList(null, null, config, Fields.DOCS);
         if (docs.isEmpty()) {
@@ -172,7 +174,7 @@ private static List<IngestDocument> parseDocs(Map<String, Object> config, RestAp
             String index = ConfigurationUtils.readStringOrIntProperty(null, null, dataMap, Metadata.INDEX.getFieldName(), "_index");
             String id = ConfigurationUtils.readStringOrIntProperty(null, null, dataMap, Metadata.ID.getFieldName(), "_id");
             String routing = ConfigurationUtils.readOptionalStringOrIntProperty(null, null, dataMap, Metadata.ROUTING.getFieldName());
-            if (restApiVersion == RestApiVersion.V_7 && dataMap.containsKey(Metadata.TYPE.getFieldName())) {
+            if (restApiVersion != RestApiVersion.V_8 && dataMap.containsKey(Metadata.TYPE.getFieldName())) {
                 deprecationLogger.compatibleCritical(
                     "simulate_pipeline_with_types",
                     "[types removal] specifying _type in pipeline simulation requests is deprecated"

server/src/main/java/org/elasticsearch/rest/action/ingest/RestSimulatePipelineAction.java

@@ -47,7 +47,7 @@ public String getName() {
     @Override
     public RestChannelConsumer prepareRequest(RestRequest restRequest, NodeClient client) throws IOException {
         Tuple<XContentType, BytesReference> sourceTuple = restRequest.contentOrSourceParam();
-        SimulatePipelineRequest request = new SimulatePipelineRequest(sourceTuple.v2(), sourceTuple.v1());
+        SimulatePipelineRequest request = new SimulatePipelineRequest(sourceTuple.v2(), sourceTuple.v1(), restRequest.getRestApiVersion());
         request.setId(restRequest.param("id"));
         request.setVerbose(restRequest.paramAsBoolean("verbose", false));
         return channel -> client.admin().cluster().simulatePipeline(request, new RestToXContentListener<>(channel));