feat: events

[toddbaert]

This PR:

• makes some changes to initialization to set providers before waiting for them to be ready, as discussed in this thread.
• implements provider events:
  • Provider authors can now optionally extend EventProvider and emit events with this.eventEmitter.emit(event, details); (and it's similar convenience methods)
  • Application authors can add handlers to clients or the API with ...on(event, handler) where handler is a java.util.function.Consumer<EventDetails> and it's convenience methods.
  • when providers finish initializing, PROVIDER_READY / PROVIDER_ERROR are emitted automatically depending on it's success.

See the tests in EventsTest.java to get a feel for the API.

Fixes: #475
Fixes: #440

[codecov]

Codecov Report

Merging #476 (7eebd01) into main (893d0da) will increase coverage by 0.78%.
The diff coverage is 98.95%.

@@             Coverage Diff              @@
##               main     #476      +/-   ##
============================================
+ Coverage     94.44%   95.23%   +0.78%     
- Complexity      268      329      +61     
============================================
  Files            25       31       +6     
  Lines           612      755     +143     
  Branches         36       37       +1     
============================================
+ Hits            578      719     +141     
- Misses           17       19       +2     
  Partials         17       17              

Flag	Coverage Δ
unittests	95.23% <98.95%> (+0.78%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...java/dev/openfeature/sdk/internal/ObjectUtils.java	100.00% <ø> (ø)
...n/java/dev/openfeature/sdk/ProviderRepository.java	98.36% <96.00%> (-1.64%)	⬇️
.../main/java/dev/openfeature/sdk/OpenFeatureAPI.java	98.90% <98.46%> (-1.10%)	⬇️
...rc/main/java/dev/openfeature/sdk/EventDetails.java	100.00% <100.00%> (ø)
...c/main/java/dev/openfeature/sdk/EventProvider.java	100.00% <100.00%> (ø)
...rc/main/java/dev/openfeature/sdk/EventSupport.java	100.00% <100.00%> (ø)
...main/java/dev/openfeature/sdk/FeatureProvider.java	100.00% <100.00%> (ø)
...rc/main/java/dev/openfeature/sdk/NoOpProvider.java	100.00% <100.00%> (ø)
...in/java/dev/openfeature/sdk/OpenFeatureClient.java	98.01% <100.00%> (+0.17%)	⬆️
...c/main/java/dev/openfeature/sdk/ProviderEvent.java	100.00% <100.00%> (ø)
... and 2 more

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more

[toddbaert]

@open-feature/sdk-java-approvers @open-feature/sdk-java-maintainers I'll be merging this tomorrow EOD unless I hear objections! If you intend to review it and you'd like me to hold-off, or you have any concerns, let me know.

This implementation is quite close the to go/js impls, and as far as I can tell is spec adherent.

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
23 Code Smells

No Coverage information
0.0% Duplication