[FIX] Fix Activesupport json encode for hash with duplicate keys

[maniSHarma7575]

Fix: #50481

Motivation / Background

This Pull Request has been created because to fix #50481

The output for the hash is inconsistent when using ActiveSupport::JSON.encode with the duplicate key in RAILS_VERSION=7.1.0. Specifically, if we examine the result below, the key 'a' appears twice in the output JSON for the same key 'a'.

For RAILS_VERSION=7.0.8, it behaves as expected. Key is only once with later value.

For example:

ActiveSupport::JSON.encode({ 'a' => 1, :a => 2 })

Result:

"{\"a\":1,\"a\":2}"

This behavior is not observed in RAILS_VERSION=7.0.8.

Checklist

Before submitting the PR make sure the following are checked:

• This Pull Request is related to one change. Changes that are unrelated should be opened in separate PRs.
• Commit message has a detailed description of what changed and why. If this PR fixes a related issue include it in the commit message. Ex: [Fix #50481]
• Tests are added or updated if you fix a bug or add a feature.
• CHANGELOG files are updated for the changed libraries if there is a behavior change or additional feature. Minor bug fixes and documentation changes should not be included.

[maniSHarma7575]

cc: @byroot

[byroot]

Thanks, I backported it to 7-1-stable. We should fix it in flori/json too though.

[maniSHarma7575]

Thanks, I backported it to 7-1-stable. We should fix it in flori/json too though.

Thanks for merging it @byroot T . This is my first contribution to rails. Looking forward to more.

Yeah, I'll do it in flori/json as well.

[maniSHarma7575]

Thanks, I backported it to 7-1-stable. We should fix it in flori/json too though.

@byroot I have fixed it in flori/json as well. Could you kindly review it?

flori/json#564

[jhawthorn]

Sorry I missed this change at the time, I don't think we should have merged this. At some point we have to have a limit on how much double checking Rails does of the user's input and I think this is well within the area we should be "garbage in/garbage out".

Being forced to support this really paints us into a corner in how we can implement this.

I'd also argue that I'd actually prefer { 'a' => 1, :a => 2 } be turned into the questionably valid JSON as "{\"a\":1,\"a\":2}" rather than either "{\"a\":1}" or "{\"a\":2}" as it would allow me to see that there is an issue with my program rather than hiding the error and making an arbitrary choice.

[byroot]

Yeah feel free to revert.

[rafaelfranca]

I reverted to not block the release