`GSON` doesn't parse correctly my `JSON` and returns `null` for some fields only.  

Indeed, I correctly get for every `doctor` the `rpps` and `code` but I have `null` for `lifenId`, `firstName` and `lastName`.  

I have a `JSON` which is a list of `doctor` looks like this :

```
[
    {
        "lifenId": "238536",
        "rpps": "10002732211",
        "firstName": "Yolande ",
        "lastName": "Couffinhal",
        "email": null,
        "postalCode": null,
        "city": null,
        "address": null,
        "code": "Médecin Neuro-psychiatrie ",
        "phone": null
    },
...
]

```

I'm sure that my `JSON` is correct because the `JSON` I receive is exactly the one I post here so these value are not null (for example, I'm not talking about the phone which is `null` in the `JSON`)  

I tried to parse manually the `JSON` to get firstName and lastName it works (obviously because I have a good `JSON`, but I wanted to be sure of that) 

There is my `data class Doctor` : 

```
data class Doctor(var phone: String,
                  var code: String,
                  var address: MutableList<String>,
                  var email: String,
                  var rpps: String,
                  var city: String,
                  var lastName: Any,
                  var firstName: Any,
                  var lifenId: String,
                  var postalCode: String) {
}  

```

My request: 

```
fun getDoctorsByName(name: String, token: String): Single<List<Doctor>> {
        val url = "lifen/name/" + name
        return repository.getDoctorsByName(url, token).compose(schedulerProvider.getSchedulersForSingle())
    }  

```

how I treat the return : 

```
disposable.add(viewModel.getDoctorsByName(search_bar.query.toString(), activity.token)
                    .doOnError {
                        Toast.makeText(activity, it.message, Toast.LENGTH_SHORT).show()
                    }
                    .subscribe(
                        { doctors ->
                            /*val list = ArrayList<Doctor>()
                            val doc = Doctor("", "","","","",doctors[0]["lastName"] as String,doctors[0]["firstName"] as String,"","") parse manually here
                            list.add(doc)
                            adapter.updateList(list)*/
                            adapter.updateList(doctors)
                            Toast.makeText(activity, "LIST COMPLETED", Toast.LENGTH_SHORT).show()
                        }, Throwable::printStackTrace
                    )

                )

```