AWS Cognito IntitiateAuth: Missing required parameter UserName
<p>When initializing an authentication to AWS Cognito, the API is rejecting my request:</p>

<pre><code>InvalidParameterException: Missing required parameter UserName
status code: 400,
</code></pre>

<p>Here is the content of the request (yes, I tried putting it everywhere, no success).</p>

<pre><code>params := &amp;cognitoidentityprovider.InitiateAuthInput{
    AuthFlow: aws.String("USER_SRP_AUTH"),              // Required
    ClientId: aws.String("xxxxxxxxxxxxxxxx"), // Required
    AuthParameters: map[string]*string{
        "username":     aws.String("myUser"), // Required
        "UserName":     aws.String("myUser"), // Required
    },
    ClientMetadata: map[string]*string{
        "username":     aws.String("myUser"), // Required
        "UserName":     aws.String("myUser"), // Required
    },
}
</code></pre>

<p>Any idea about what would be the problem please?
Considering to the doc (<a href="https://docs.aws.amazon.com/cognito/latest/developerguide/cognito-dg-pdf.pdf" rel="noreferrer">https://docs.aws.amazon.com/cognito/latest/developerguide/cognito-dg-pdf.pdf</a>), <code>username</code> should be in AuthParameters along with <code>srpA</code>. Would it be possible that the problem comes from srpA? If so, what is this? It looks like that it is the password.</p>