feat!: add provider event details

[jescriba]

This PR

• Aims to address this enhancement: [Enhancement] Add ProviderEventDetails to ProviderEvent #76
• The Open Feature spec outlines Event data emitted with ProviderEvent: https://openfeature.dev/specification/types#provider-event-details

Questions

• According to the spec, the event metadata value is more limited than allowed feature flag value types (like object and date are unavailable). If I wanted to subscribe to a feature flag's configuration - would I be expected to just query all the changed flags emitted from a configuration_changed event? Something like:

switch providerEvent {
case .configurationChanged(let details):
    for details?.flags_changed.each { |flag| in 
        client.getValue(key: flag, defaultValue: flagDefault) 
        // Use the new flag value for the caller
    }
}

Or could the event metadata support flag values something like:

switch providerEvent {
case .configurationChanged(let details):
    for details?.flags_changed.each { |flag| in 
        details.eventMetadata[flag] // UpdatedFlagValue
    }
}

Breaking Changes

• ProviderEvent now contains an associated value for ProviderEventDetails. This payload includes the error information now. So consumers of this API - will need to pull the errorCode and message from the ProviderEventDetails struct

New to this repo and spec so open to any feedback 😅

[beeme1mr]

Hey @jescriba, I've marked this as breaking by adding a ! to the PR title.

[beeme1mr]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces a significant and beneficial breaking change by adding ProviderEventDetails to ProviderEvent, aligning the Swift SDK more closely with the OpenFeature specification. The refactoring to consolidate FlagMetadataValue and EventMetadataValue into a single MetadataValue is an excellent improvement for maintainability and code reuse. The addition of a MockProvider and new tests significantly enhances the test suite's quality. I've provided a few suggestions to further improve the new tests and a minor refactoring suggestion for better code style. Overall, this is a well-executed and valuable contribution.

[beeme1mr]

The change looks good and better aligns with the spec.

[jescriba]

Gemini comments were good so I updated the PR accordingly 👍

[fabriziodemaria]

I think it would be nice to add the Provider Name to comply to the spec 100%. But this is still a step in the right direction, so I am happy to merge this to begin with

[fabriziodemaria]

the event metadata value is more limited than allowed feature flag value types

I am probably not the right person to comment on the specifications, but I assumed that the Metadata is not meant to be mapped to a Flag's value: in this sense, the types compatibility is also, perhaps, not mandatory or expected.
Albeit if a customer wanted to report the value there, I agree this is currently a limitation

[jescriba]

Addressed comments 👍 Let me know if there's any remaining changes I should make to land this work

[beeme1mr]

Hey @jescriba, thanks for the contribution. I've merged the PR and the changes will be included in the next release.

Would you be interested in joining the org? It doesn't come with any obligations but is the first step in the contributing ladder. It also allows us to include you in reviews and @ mention you in comments.