Add MerchantRepository for holding BraintreeClient properties

[tdchow]

Summary of changes

• Create MerchantRepository which holds properties that were previously in BraintreeClient
• MerchantRepository singleton that keeps fields in memory, allowing any class to access its values via dependency injection

Checklist

• Added a changelog entry
• Relevant test coverage

Authors

List GitHub usernames for everyone who contributed to this pull request.

[tdchow]

Not sure if there's a clearer name for this class.

[sarahkoop]

Maybe a doc string for our internal understanding of what this class is for?

[jaxdesmarais]

➕ 1 I think some docstrings would help, I don't have any issues with the name since this naming seems like a common pattern on Android.

[tdchow]

does the @RestrictTo(RestrictTo.Scope.LIBRARY_GROUP) prevent dokka from publishing to the generated docs?

[tdchow]

It looks like those internal classes do get published :(

https://braintree.github.io/braintree_android/BraintreeCore/com.braintreepayments.api.core/index.html

I'll look to see if there's a way to prevent this.

[saperi22]

does the @RestrictTo(RestrictTo.Scope.LIBRARY_GROUP) prevent dokka from publishing to the generated docs?

Not sure if it does that, but you could add @suppress in the docs to suppress it.
Also see: Kotlin/dokka#2404 for a custom implementation we can do to suppress all @RestrictTo annotated methods.

[tdchow]

Dang, I thought there'd be support directly in Dokka for that. I've added some docs for this class.

I'll create a tech debt ticket for possibly adding a custom implementation to suppress based on the annotation.