[CI] EncryptedRepositorySecretIntegTests testSnapshotFailsForMasterFailoverWithWrongPassword failing

[ywangd]

It only failed once in last 7 days. But the exception of ConcurrentModificationException could suggest subtle racing issue. Hence I am raising the issue so that more knowledgeable people of this area have a chance to look at it.
It does not have a repro line. So I just tested locally with the following and it did not reproduce.

./gradlew ':x-pack:plugin:repository-encrypted:internalClusterTest' --tests "org.elasticsearch.repositories.encrypted.EncryptedRepositorySecretIntegTests.testWrongRepositoryPassword"

Build scan:
https://gradle-enterprise.elastic.co/s/tuyh22k3b7kl2/tests/:x-pack:plugin:repository-encrypted:internalClusterTest/org.elasticsearch.repositories.encrypted.EncryptedRepositorySecretIntegTests/testSnapshotFailsForMasterFailoverWithWrongPassword

Reproduction line:
null

Applicable branches:
7.x

Reproduces locally?:
No

Failure history:
https://gradle-enterprise.elastic.co/scans/tests?tests.container=org.elasticsearch.repositories.encrypted.EncryptedRepositorySecretIntegTests&tests.test=testSnapshotFailsForMasterFailoverWithWrongPassword

Failure excerpt:

junit.framework.AssertionFailedError: Unexpected exception type, expected SnapshotMissingException but got java.util.ConcurrentModificationException

  at __randomizedtesting.SeedInfo.seed([90920412F13FF1B4:86DC1B629ADB5258]:0)
  at org.apache.lucene.util.LuceneTestCase.expectThrows(LuceneTestCase.java:2746)
  at org.apache.lucene.util.LuceneTestCase.expectThrows(LuceneTestCase.java:2734)
  at org.elasticsearch.repositories.encrypted.EncryptedRepositorySecretIntegTests.testSnapshotFailsForMasterFailoverWithWrongPassword(EncryptedRepositorySecretIntegTests.java:693)
  at sun.reflect.NativeMethodAccessorImpl.invoke0(NativeMethodAccessorImpl.java:-2)
  at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  at java.lang.reflect.Method.invoke(Method.java:498)
  at com.carrotsearch.randomizedtesting.RandomizedRunner.invoke(RandomizedRunner.java:1750)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$8.evaluate(RandomizedRunner.java:938)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$9.evaluate(RandomizedRunner.java:974)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$10.evaluate(RandomizedRunner.java:988)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.util.TestRuleSetupTeardownChained$1.evaluate(TestRuleSetupTeardownChained.java:49)
  at org.apache.lucene.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:45)
  at org.apache.lucene.util.TestRuleThreadAndTestName$1.evaluate(TestRuleThreadAndTestName.java:48)
  at org.apache.lucene.util.TestRuleIgnoreAfterMaxFailures$1.evaluate(TestRuleIgnoreAfterMaxFailures.java:64)
  at org.apache.lucene.util.TestRuleMarkFailure$1.evaluate(TestRuleMarkFailure.java:47)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$StatementRunner.run(ThreadLeakControl.java:368)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl.forkTimeoutingTask(ThreadLeakControl.java:817)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$3.evaluate(ThreadLeakControl.java:468)
  at com.carrotsearch.randomizedtesting.RandomizedRunner.runSingleTest(RandomizedRunner.java:947)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$5.evaluate(RandomizedRunner.java:832)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$6.evaluate(RandomizedRunner.java:883)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$7.evaluate(RandomizedRunner.java:894)
  at org.apache.lucene.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:45)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.util.TestRuleStoreClassName$1.evaluate(TestRuleStoreClassName.java:41)
  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 com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.util.TestRuleAssertionsRequired$1.evaluate(TestRuleAssertionsRequired.java:53)
  at org.apache.lucene.util.TestRuleMarkFailure$1.evaluate(TestRuleMarkFailure.java:47)
  at org.apache.lucene.util.TestRuleIgnoreAfterMaxFailures$1.evaluate(TestRuleIgnoreAfterMaxFailures.java:64)
  at org.apache.lucene.util.TestRuleIgnoreTestSuites$1.evaluate(TestRuleIgnoreTestSuites.java:54)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$StatementRunner.run(ThreadLeakControl.java:368)
  at java.lang.Thread.run(Thread.java:748)

  Caused by: java.util.ConcurrentModificationException: (No message provided)

    at java.util.HashMap$HashIterator.nextNode(HashMap.java:1445)
    at java.util.HashMap$EntryIterator.next(HashMap.java:1479)
    at java.util.HashMap$EntryIterator.next(HashMap.java:1477)
    at java.util.AbstractMap.hashCode(AbstractMap.java:530)
    at java.util.Arrays.hashCode(Arrays.java:4146)
    at java.util.Objects.hash(Objects.java:128)
    at org.elasticsearch.snapshots.SnapshotInfo.hashCode(SnapshotInfo.java:999)
    at java.util.HashMap.hash(HashMap.java:339)
    at java.util.HashMap.put(HashMap.java:612)
    at java.util.HashSet.add(HashSet.java:220)
    at org.elasticsearch.action.admin.cluster.snapshots.get.TransportGetSnapshotsAction.snapshots(TransportGetSnapshotsAction.java:193)
    at org.elasticsearch.action.admin.cluster.snapshots.get.TransportGetSnapshotsAction.lambda$loadSnapshotInfos$1(TransportGetSnapshotsAction.java:159)
    at org.elasticsearch.action.ActionRunnable.lambda$supply$0(ActionRunnable.java:47)
    at org.elasticsearch.action.ActionRunnable$2.doRun(ActionRunnable.java:62)
    at org.elasticsearch.common.util.concurrent.ThreadContext$ContextPreservingAbstractRunnable.doRun(ThreadContext.java:732)
    at org.elasticsearch.common.util.concurrent.AbstractRunnable.run(AbstractRunnable.java:26)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at java.lang.Thread.run(Thread.java:748)

[elasticmachine]

Pinging @elastic/es-distributed (Team:Distributed)