**Build scan:**
https://gradle-enterprise.elastic.co/s/rrbldaxcklpvk/tests/:x-pack:qa:rolling-upgrade:v8.2.4%23twoThirdsUpgradedTest/org.elasticsearch.upgrades.MLModelDeploymentsUpgradeIT/testTrainedModelDeployment

**Reproduction line:**
`./gradlew ':x-pack:qa:rolling-upgrade:v8.2.4#twoThirdsUpgradedTest' -Dtests.class="org.elasticsearch.upgrades.MLModelDeploymentsUpgradeIT" -Dtests.method="testTrainedModelDeployment" -Dtests.seed=B48E616E1A60493F -Dtests.bwc=true -Dtests.locale=no-NO -Dtests.timezone=America/Kralendijk -Druntime.java=17`

**Applicable branches:**
master

**Reproduces locally?:**
Didn't try

**Failure history:**
https://gradle-enterprise.elastic.co/scans/tests?tests.container=org.elasticsearch.upgrades.MLModelDeploymentsUpgradeIT&tests.test=testTrainedModelDeployment

**Failure excerpt:**
```
org.elasticsearch.client.ResponseException: method [POST], host [http://[::1]:35509], URI [/_ml/trained_models/upgrade-deployment-test/deployment/_infer], status line [HTTP/1.1 404 Not Found]
{"error":{"root_cause":[{"type":"status_exception","reason":"[upgrade-deployment-test] unable to find deployment task for inference please stop and start the deployment or try again momentarily"}],"type":"status_exception","reason":"[upgrade-deployment-test] unable to find deployment task for inference please stop and start the deployment or try again momentarily"},"status":404}

  at __randomizedtesting.SeedInfo.seed([B48E616E1A60493F:4F5627313BA0F3A8]:0)
  at org.elasticsearch.client.RestClient.convertResponse(RestClient.java:347)
  at org.elasticsearch.client.RestClient.performRequest(RestClient.java:313)
  at org.elasticsearch.client.RestClient.performRequest(RestClient.java:288)
  at org.elasticsearch.upgrades.MLModelDeploymentsUpgradeIT.infer(MLModelDeploymentsUpgradeIT.java:249)
  at org.elasticsearch.upgrades.MLModelDeploymentsUpgradeIT.assertInfer(MLModelDeploymentsUpgradeIT.java:149)
  at org.elasticsearch.upgrades.MLModelDeploymentsUpgradeIT.testTrainedModelDeployment(MLModelDeploymentsUpgradeIT.java:82)
  at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(NativeMethodAccessorImpl.java:-2)
  at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
  at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  at java.lang.reflect.Method.invoke(Method.java:568)
  at com.carrotsearch.randomizedtesting.RandomizedRunner.invoke(RandomizedRunner.java:1758)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$8.evaluate(RandomizedRunner.java:946)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$9.evaluate(RandomizedRunner.java:982)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$10.evaluate(RandomizedRunner.java:996)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.tests.util.TestRuleSetupTeardownChained$1.evaluate(TestRuleSetupTeardownChained.java:44)
  at org.apache.lucene.tests.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
  at org.apache.lucene.tests.util.TestRuleThreadAndTestName$1.evaluate(TestRuleThreadAndTestName.java:45)
  at org.apache.lucene.tests.util.TestRuleIgnoreAfterMaxFailures$1.evaluate(TestRuleIgnoreAfterMaxFailures.java:60)
  at org.apache.lucene.tests.util.TestRuleMarkFailure$1.evaluate(TestRuleMarkFailure.java:44)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$StatementRunner.run(ThreadLeakControl.java:375)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl.forkTimeoutingTask(ThreadLeakControl.java:824)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$3.evaluate(ThreadLeakControl.java:475)
  at com.carrotsearch.randomizedtesting.RandomizedRunner.runSingleTest(RandomizedRunner.java:955)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$5.evaluate(RandomizedRunner.java:840)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$6.evaluate(RandomizedRunner.java:891)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$7.evaluate(RandomizedRunner.java:902)
  at org.apache.lucene.tests.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.tests.util.TestRuleStoreClassName$1.evaluate(TestRuleStoreClassName.java:38)
  at com.carrotsearch.randomizedtesting.rules.NoShadowingOrOverridesOnMethodsRule$1.evaluate(NoShadowingOrOverridesOnMethodsRule.java:40)
  at com.carrotsearch.randomizedtesting.rules.NoShadowingOrOverridesOnMethodsRule$1.evaluate(NoShadowingOrOverridesOnMethodsRule.java:40)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.tests.util.TestRuleAssertionsRequired$1.evaluate(TestRuleAssertionsRequired.java:53)
  at org.apache.lucene.tests.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
  at org.apache.lucene.tests.util.TestRuleMarkFailure$1.evaluate(TestRuleMarkFailure.java:44)
  at org.apache.lucene.tests.util.TestRuleIgnoreAfterMaxFailures$1.evaluate(TestRuleIgnoreAfterMaxFailures.java:60)
  at org.apache.lucene.tests.util.TestRuleIgnoreTestSuites$1.evaluate(TestRuleIgnoreTestSuites.java:47)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$StatementRunner.run(ThreadLeakControl.java:375)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl.lambda$forkTimeoutingTask$0(ThreadLeakControl.java:831)
  at java.lang.Thread.run(Thread.java:833)

```
x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/inference/assignment/TrainedModelAssignmentMetadata.java
* 2.0; you may not use this file except in compliance with the Elastic License
 * 2.0.
 */
package org.elasticsearch.xpack.ml.inference.assignment;
import org.elasticsearch.ResourceAlreadyExistsException;
import org.elasticsearch.ResourceNotFoundException;
import org.elasticsearch.Version;
import org.elasticsearch.cluster.ClusterState;
import org.elasticsearch.cluster.Diff;
import org.elasticsearch.cluster.DiffableUtils;
import org.elasticsearch.cluster.NamedDiff;
import org.elasticsearch.cluster.SimpleDiffable;
import org.elasticsearch.cluster.metadata.Metadata;
import org.elasticsearch.common.Strings;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.io.stream.StreamOutput;
import org.elasticsearch.xcontent.XContentBuilder;
import org.elasticsearch.xcontent.XContentParser;
import org.elasticsearch.xpack.core.ml.inference.assignment.TrainedModelAssignment;
import org.elasticsearch.xpack.core.ml.utils.ExceptionsHelper;
import java.io.IOException;
import java.util.Collections;
import java.util.EnumSet;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Objects;
import java.util.Optional;
import java.util.TreeMap;
import static org.elasticsearch.cluster.metadata.Metadata.ALL_CONTEXTS;
public class TrainedModelAssignmentMetadata implements Metadata.Custom {