Add Client option for access_token_class

[jonspalmer]

The Problem

There is no way to use OAuth2::Client strategies such as auth_code AND supply a custom access_token_class.

OAuth2::Client.get_token has an optional argument for the access_token_class to instantiate.
However, callers of it have to know to use it and none of the strategies do so. This means the anyone needing a custom access_token_class, #243 or #511, need to jump through hoops to get the behavior they want. For example subclassing OAuth2::Client just to change the default class

What I did

Added a new option, access_token_class, to OAuth2::Client which is used as the default access_token_class for all calls to get_token.

This is a safe, non-breaking change.

[coveralls]

Pull Request Test Coverage Report for Build 1040

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 0.0%

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Totals
Change from base Build 1038:	0.0%
Covered Lines:	0
Relevant Lines:	0

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💛 - Coveralls

[pboling]

@jonspalmer Would it be too complex to bother trying this on the 1-4-stable branch?

[jonspalmer]

@jonspalmer Would it be too complex to bother trying this on the 1-4-stable branch?

@pboling #518 provides a better solution to this problem and is already in 1-4-stable. That change is going to merge conflict with this change in master and IMO should replace this change entirely. The point being that the proc approach in #518 allows you to return any flavor of AccessToken you desire.

[pboling]

@jonspalmer Thanks for the heads up, again, and sorry for the long delay in addressing it. v2 is moving ahead at a very slow pace because my personal use case for this gem is vanishingly thin*. I would need far more community support to move it forward more quickly.

I'm going to work on parity between 1-4-stable and v2 (master, soon to be main) now.

* none of the work done, or bugs fixed, since I took over maintenance have affected my use case. I'm donating time to the community because I want the community to survive, and I know this gem matters a great deal to many important projects.