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var refreshToken = await _userManager.GetAuthenticationTokenAsync(user, "MyApp", "RefreshToken");
var isValid = await _userManager.VerifyUserTokenAsync(user, "MyApp", "RefreshToken", refreshToken );
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await _userManager.RemoveAuthenticationTokenAsync(user, "MyApp", "RefreshToken");
var newRefreshToken = await _userManager.GenerateUserTokenAsync(user, "MyApp", "RefreshToken");
await _userManager.SetAuthenticationTokenAsync(user, "MyApp", "RefreshToken", newRefreshToken);
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identity.AddTokenProvider("MyApp", typeof(DataProtectorTokenProvider<User>)