Unable to generate Access Token with .NET Core

[Anonymous]

I'm trying to Embed Power BI Report using .NET Core Web Application and Angular. For this I used PowerBIEmbedded_AppOwnsData( .NET MVC) sample and successfully able to generate tokens and embed the report there

But in .NET Core Application as there is no AcquireTokenAsync method so I refered this Embed Power BI dashboard in ASP.Net core  which uses Resource Owner Password Credentials Grant flow and in the below coding using the same request body as I used earlier in PowerBIEmbedded_AppOwnsData(.NET) App.

 private async Task<OAuthResult> AuthenticateAsync()
        {
            var oauthEndpoint = new Uri("https://login.microsoftonline.com/common/oauth2/token");
            using (var client = new HttpClient())
            {
                var result = await client.PostAsync(oauthEndpoint, new FormUrlEncodedContent(new[]
                 {
                     new KeyValuePair<string,string>("resource", "https://analysis.windows.net/powerbi/api"),
                     new KeyValuePair<string,string>("client_id", ApplicationId),
                     new KeyValuePair<string,string>("client_secret", ApplicationSecret),
                     new KeyValuePair<string,string>("grant_type", "password"),
                     new KeyValuePair<string,string>("username", Username),
                     new KeyValuePair<string,string>("password", Password),
                     new KeyValuePair<string,string>("scope", "openid")
                 }
                ));

                var content = await result.Content.ReadAsStringAsync();
                return JsonConvert.DeserializeObject<OAuthResult>(content);
            }

        }

But this time I am getting an error response which was succesful in .NET Sample

{
    "error": "invalid_grant",
    "error_description": "AADSTS50126: Invalid username or password.\r\nTrace ID: e4813657-d71a-480c-87a2-1140a49b6f00\r\nCorrelation ID: ba79a622-32e2-4a12-b7fd-65a21a99f378\r\nTimestamp: 2019-05-07 09:46:05Z",
    "error_codes": [
        50126
    ],
    "timestamp": "2019-05-07 09:46:05Z",
    "trace_id": "e4813657-d71a-480c-87a2-1140a49b6f00",
    "correlation_id": "ba79a622-32e2-4a12-b7fd-65a21a99f378"
}

Please Help