[google-auth-library-java] Flaky Test: ClientSideCredentialAccessBoundaryFactoryTest.refreshCredentialsIfRequired_blockingMultiThread

[lqiu96]

Flaky test on Windows: https://github.com/googleapis/google-auth-library-java/actions/runs/18510520808/job/52750115346?pr=1828

[INFO] Running com.google.auth.credentialaccessboundary.ClientSideCredentialAccessBoundaryFactoryTest
Error:  Tests run: 29, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 3.554 s <<< FAILURE! -- in com.google.auth.credentialaccessboundary.ClientSideCredentialAccessBoundaryFactoryTest
Error:  com.google.auth.credentialaccessboundary.ClientSideCredentialAccessBoundaryFactoryTest.refreshCredentialsIfRequired_blockingMultiThread -- Time elapsed: 1.326 s <<< FAILURE!
java.lang.AssertionError: expected:<2> but was:<3>