Verify we have tests that ensure the hashCode function outputs never change.

[nickpoorman]

Per the incident, write test to ensure the output of this function doesn't change: https://github.com/hashgraph/hedera-services/pull/5968/files#diff-5cb4fe4feeb3706107fbe96b51767faa909d214b0ce57c41308eb1d835337792R345

[nickpoorman]

Add comment to this method to ensure nobody changes the values to make the test work in the future. https://github.com/hashgraph/hedera-services/blob/develop/hedera-node/hedera-mono-service/src/test/java/com/hedera/node/app/service/mono/state/virtual/ContractKeyTest.java#L56

[david-bakin-sl]

Suggestion: Invent a new annotation, e.g., @ContractInvariant or @ServicesInvariant that would annotate tests, such as the one proposed here, and other similar ones, to indicate that they must never be changed.

Advantages over a simple comment would be that you could then have a script that would be run each release tag that confirmed that the files that had a test annotated this way didn't change (i.e., had no new commits). Thus it would enforce the meaning more than a comment would. (If you remembered to run the script.) (Such annotated tests would need to be isolated in their own test class away from unannotated tests.)

[nickpoorman]

Added your suggestion @david-bakin-sl to the list of items we should tackle as part of testing.