JDK 26 relaxed the implementation of CancelRequestTest::isCancelled to look for the expected exception down the whole exception chain.

It would be beneficial to import this change (part of JEP 517 - so cannot be handled by usual backports) to earlier version.

At the same time - logging the exception that does not conform to the expectation would be beneficial - in particular to see if it has anything in its call chain that was not considered.