[ML] [7.x] Only emit deprecation warning if there was actual change of a datafeed's job_id. (elastic#44755)

* Only emit deprecation warning if there was actual change of a datafeed's job_id.
* Add @deprecated annotation to DatafeedUpdate.Builder#setJobId method

Author: przemekwitek

client/rest-high-level/src/main/java/org/elasticsearch/client/ml/datafeed/DatafeedUpdate.java

@@ -287,6 +287,7 @@ public Builder(DatafeedUpdate config) {
             this.delayedDataCheckConfig = config.delayedDataCheckConfig;
         }
 
+        @Deprecated
         public Builder setJobId(String jobId) {
             this.jobId = jobId;
             return this;

client/rest-high-level/src/test/java/org/elasticsearch/client/MachineLearningIT.java

@@ -478,6 +478,11 @@ public void testUpdateDatafeed_UpdatingJobIdIsDeprecated() throws Exception {
         DatafeedConfig datafeedConfig = DatafeedConfig.builder(datafeedId, jobId).setIndices("some_data_index").build();
         execute(new PutDatafeedRequest(datafeedConfig), machineLearningClient::putDatafeed, machineLearningClient::putDatafeedAsync);
 
+        DatafeedUpdate datafeedUpdateWithUnchangedJobId = DatafeedUpdate.builder(datafeedId).setJobId(jobId).build();
+        execute(new UpdateDatafeedRequest(datafeedUpdateWithUnchangedJobId),
+            machineLearningClient::updateDatafeed,
+            machineLearningClient::updateDatafeedAsync);
+
         DatafeedUpdate datafeedUpdateWithChangedJobId = DatafeedUpdate.builder(datafeedId).setJobId(anotherJobId).build();
         WarningFailureException exception = expectThrows(
             WarningFailureException.class,

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/datafeed/DatafeedUpdate.java

@@ -110,9 +110,6 @@ private DatafeedUpdate(String id, String jobId, TimeValue queryDelay, TimeValue
         this.scrollSize = scrollSize;
         this.chunkingConfig = chunkingConfig;
         this.delayedDataCheckConfig = delayedDataCheckConfig;
-        if (jobId != null) {
-            deprecationLogger.deprecated(DEPRECATION_MESSAGE_ON_JOB_ID_UPDATE);
-        }
     }
 
     public DatafeedUpdate(StreamInput in) throws IOException {
@@ -304,6 +301,9 @@ public DatafeedConfig apply(DatafeedConfig datafeedConfig, Map<String, String> h
 
         DatafeedConfig.Builder builder = new DatafeedConfig.Builder(datafeedConfig);
         if (jobId != null) {
+            if (datafeedConfig.getJobId() != null && datafeedConfig.getJobId().equals(jobId) == false) {
+                deprecationLogger.deprecated(DEPRECATION_MESSAGE_ON_JOB_ID_UPDATE);
+            }
             builder.setJobId(jobId);
         }
         if (queryDelay != null) {

x-pack/plugin/src/test/resources/rest-api-spec/test/ml/datafeeds_crud.yml

@@ -215,6 +215,16 @@ setup:
             "indexes":["index-foo"],
             "scroll_size": 2000
           }
+  - match: { job_id: "datafeeds-crud-1" }
+
+  - do:
+      ml.update_datafeed:
+        datafeed_id: test-datafeed-1
+        body:  >
+          {
+            "job_id": "datafeeds-crud-1"
+          }
+  - match: { job_id: "datafeeds-crud-1" }
 
   - do:
       warnings: