TokenAuthIntegTests testExpiredTokensDeletedAfterExpiration failure

[davidkyle]

Build scan:
https://gradle-enterprise.elastic.co/s/ashtsylpihoek

Repro line:

./gradlew ':x-pack:plugin:security:test' --tests "org.elasticsearch.xpack.security.authc.TokenAuthIntegTests.testExpiredTokensDeletedAfterExpiration" \
  -Dtests.seed=46B9C42D9927439 \
  -Dtests.security.manager=true \
  -Dtests.locale=es \
  -Dtests.timezone=America/Lower_Princes \
  -Dcompiler.java=14 \
  -Druntime.java=11

Reproduces locally?:
No

Applicable branches:
7.7

Failure history:
Rare, once in the last 30 days so I will not mute the test today

Possibly related to #55816

Failure excerpt:

java.lang.AssertionError: 
Expected: <0>
     but: was <1>
	at __randomizedtesting.SeedInfo.seed([46B9C42D9927439:54A885BE2D43B28]:0)
	at org.hamcrest.MatcherAssert.assertThat(MatcherAssert.java:18)
	at org.junit.Assert.assertThat(Assert.java:956)
	at org.junit.Assert.assertThat(Assert.java:923)
	at org.elasticsearch.xpack.security.authc.TokenAuthIntegTests.testExpiredTokensDeletedAfterExpiration(TokenAuthIntegTests.java:226)

[elasticmachine]

Pinging @elastic/es-security (:Security/Authentication)

[dimitris-athanasiou]

Another failure:

Build scan: https://gradle-enterprise.elastic.co/s/3nxloq2igu22k

Build link: https://elasticsearch-ci.elastic.co/job/elastic+elasticsearch+7.9+multijob-unix-compatibility/os=debian-8&&immutable/30/console

[tvernum]

I've merged a change (#60496) which will improve this error message.

It's currently failing because a list of errors should be empty, but isn't.
But the code asserts on the .size() of the list, which leads to expected: <0> but: was <1> messages.
It now asserts using Matchers.empty() which will include the value of the elements in the list (the unexpected errors) in the message.