Fix flaky test org.apache.helix.rest.server.TestInstancesAccessor #2644

[hofi1]

Issues

• My PR addresses the following Helix issues and references them in the PR description:

Fixes #2644

Description

This fix changes the assertion of the tests. Sets return the elements in a non-deterministic order, which means that this assertion is not correct, because it checks whether the collections contain the same elements in the same order. This leads to a flaky test. To fix this problem, the assertion has been rewritten to check if the collections contain the same amount of elements as well as booth collections contain all values of the other collection.

This problem was found by the NonDex Engine – to reproduce run

mvn -pl helix-rest edu.illinois:nondex-maven-plugin:2.1.1:nondex -Dtest=org.apache.helix.rest.server.TestInstancesAccessor

Tests

There have been no tests added, one test condition was changed.

• The following is the result of the "mvn test" command on the appropriate module:

[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 02:54 min
[INFO] Finished at: 2023-10-04T23:01:45-05:00
[INFO] ------------------------------------------------------------------------

[junkaixue]

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