I am trying to use AppAuth-Android to authenticate with the Fitbit Web API.

I call AuthorizationService.performAuthorizationRequest() to show the Fitbit OAuth interface:

val authEndpoint = Uri.parse(config.FITBIT_AUTH_URL)
val tokenEndpoint = Uri.parse(config.FITBIT_TOKEN_URL)
val redirectUrl = Uri.parse(config.FITBIT_REDIRECT_URL)

val authConfig = AuthorizationServiceConfiguration(authEndpoint, tokenEndpoint)

val request = AuthorizationRequest.Builder(authConfig, config.FITBIT_CLIENT_ID, ResponseTypeValues.CODE, redirectUrl)
        .setPrompt("consent")
        .setScope(config.FITBIT_SCOPES.joinToString((" ")))
        .build()

val completionIntent = PendingIntent.getActivity(
        this, 0,
        Intent(this, AuthorizeFitbitActivity::class.java).apply {
            flags = Intent.FLAG_ACTIVITY_CLEAR_TOP or Intent.FLAG_ACTIVITY_SINGLE_TOP or Intent.FLAG_ACTIVITY_NEW_TASK
        },
        PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_MUTABLE
)
val cancelIntent = PendingIntent.getActivity(
        this, 1,
        Intent(this, AuthorizeFitbitActivity::class.java).apply {
            flags = Intent.FLAG_ACTIVITY_CLEAR_TOP or Intent.FLAG_ACTIVITY_SINGLE_TOP or Intent.FLAG_ACTIVITY_NEW_TASK
            putExtra(EXTRA_AUTH_CANCELLED, true)
        },
        PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_MUTABLE
)

this.fitbitAuthService.performAuthorizationRequest(request, completionIntent, cancelIntent)

The interface does show, but in a different task, so when the user finishes and dismisses the authorization web interface, they now have two instances of my app.

How can I either keep the web interface in my app's task, or close the task after they dismiss it so I'm back to a single instance?