feat: support multiple audiences

[peterphanouvong]

Explain your changes

• allow passing in audiences as string of audiences separated by whitespace
• set the url params in a way to allow for more than 1 audience

Suppose there is a related issue with enough detail for a reviewer to understand your changes fully. In that case, you can omit an explanation and instead include either “Fixes #XX” or “Updates #XX” where “XX” is the issue number.

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[coel]

@peterphanouvong, I'd suggest instead of doing a string split convert the property config.audience to be an array. It could be string or string[] to maintain backwards compatibility.

So for OAuth2FlowOptions, the property becomes:

audience?: string | string[];

Then check later if it is an array or not. Could be a condition or do something to make an array if not like:

const audienceArray = Array.isArray(this.config.audience) ? this.config.audience : [this.config.audience];

[DaveOrDead]

@coel I guess a lot of the time the audience is being passed in via a .env file which would mean declaring

AUDIENCE=['a','b']

and then having to do some nastiness to convert that environment variable string into an array?

[coel]

@DaveOrDead , I think if it is nasty we shouldn't force it onto users in the base SDK. It seems like whitespace is valid in an audience, though we don't seem to handle it. We might need to patch that up.

If we have helpers to deal with .env I think it should happen in the layer .env is introduced.

[DaveOrDead]

@coel I'm ok with that @peterphanouvong are you ok to update?