[Auth] Reported username depends on AuthFlow used

[mattcreaser]

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Language and Async Model

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Amplify Categories

Authentication

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Describe the bug

If you sign in to a user using an email address (or phone number) as the sign in attribute when using the USER_AUTH flow then when you call Amplify.Auth.getCurrentUser().username the value returned will be the attribute to used to sign in. With all other flows the value returned is the actual username.

Reproduction steps (if applicable)

1. User a userpool with email and/or phonenumber as a sign in attribute. Have USER_AUTH and USER_SRP_AUTH both enabled in the app client.
2. Use an email address (or phone number) to sign in with a created user via the USER_AUTH flow.
3. Call getCurrentUser() and observe the username.
4. Sign out
5. Sign in to the same user using USER_SRP_AUTH.
6. Call getCurrentUser() and observe the username.

Expected: The username is the same in both cases since it's the same user.
Actual: In USER_AUTH the username is reported as the email address, in USER_SRP_AUTH it's the username (which may be a UUID if no username was supplied at sign up).

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[github-actions]

This issue was opened by a maintainer of this repository; updates will be posted here. If you are also experiencing this issue, please comment here with any relevant information so that we're aware and can prioritize accordingly.

[mattcreaser]

This impacts more than just the username returned in getCurrentUser. Internally we store various pieces of information using the "username" as the key. Using an alias attribute like email address as a key is not good because that is not a constant value for a given user.