NullPointerException

> Please provide us with the following information:
> ---------------------------------------------------------------

### This issue is for a: (mark with an `x`)
```
- [ x] bug report -> please search issues before submitting
- [ ] feature request
- [ ] documentation issue or request
- [ ] regression (a behavior that used to work and stopped in a new release)
```

### Minimal steps to reproduce
>
git clone project, load in Android Studio, update B2CConfiguration.java (Custom Policy), build/run the app in Android Studio, select B2C, run flow

### Any log messages given by the failure
>
2020-04-09 15:03:25.392 9962-9962/com.azuresamples.msalandroidapp D/B2CModeFragment: Authentication failed: com.microsoft.identity.client.exception.MsalClientException: Attempt to invoke virtual method 'long java.lang.Long.longValue()' on a null object reference

This is the same issue as observed in another MSAL sample https://github.com/Azure-Samples/ms-identity-android-native/issues/15
### Expected/desired behavior
>
MSAL auth to work.

### OS and Version?
> Windows 7, 8 or 10. Linux (which distribution). macOS (Yosemite? El Capitan? Sierra?)
Win10
### Versions
>
10.0.18362.720
### Mention any other details that might be useful
Android Studio 3.6.2

> ---------------------------------------------------------------
> Thanks! We'll be in touch soon.

Comece com B2CConfiguration.java e com o fluxo de autenticação de B2CModeFragment descrito no relatório. Reproduza o fluxo de custom-policy no Android Studio e inspecione o valor Long null registrado. Está concluído quando o fluxo de autenticação do MSAL for concluído com sucesso sem a NullPointerException.

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