[codegen] Fix 'super.HashCode' for oneOf and allOf Implementations

[jburgess]

This fixes various client and server generators which use allOf and discriminator patterns as identified in #5587

This error occurs as the hasVars boolean is not set for models which contain extension patterns. This fix simply sets the boolean at the end of code generation bases on the existence of variables after post-processing these special object types.

PR checklist

• Read the contribution guidelines.
• If contributing template-only or documentation-only changes which will change sample output, build the project before.
• Run the shell script(s) under ./bin/ (or Windows batch scripts under.\bin\windows) to update Petstore samples related to your fix. This is important, as CI jobs will verify all generator outputs of your HEAD commit, and these must match the expectations made by your contribution. You only need to run ./bin/{LANG}-petstore.sh, ./bin/openapi3/{LANG}-petstore.sh if updating the code or mustache templates for a language ({LANG}) (e.g. php, ruby, python, etc).
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[jburgess]

@wing328 I am hoping you can provide a recommendation. This PR consists of a one line change to the DefaultCodegen.java. I ran the run_all_petstore from the PR checklist and this added a slew of changes to this PR. These all appear to be related to the version bump from 4.3.0-SNAPSHOT to 4.3.1-SNAPSHOT. I would have expected these changes to already be present. Can you provide a recommendation to slim down this PR to only the relevant changes? Thanks in advance!

[wing328]

@jburgess please revert the changes related to run-all-petstore script as it should be run by the CIs only.

Please run ./bin/utils/ensure-up-to-date instead.

[wing328]

Looks like you're including commits not authored by you in this PR (due to rebase?)

I would suggest you file a new PR from the latest master instead.

[jburgess]

Thanks @wing328. Opened #5830