gistfile1.txt

// API class
    @retrofit2.http.PUT("/api/v1/user/logout")
    fun logout( @Header("Authorization") token: String) : io.reactivex.Observable<Void>

// Repository class
    fun logout(token: String) : io.reactivex.Observable<Void> {
        return apiService.logout("Bearer " + token)
    }

// network wrapper class
   fun logout( context: Context, successHandler : () -> Unit, errorHandler: () -> Unit  )  {
        if (token != null) {
            compositeDisposable.add(
            repository.logout(token!!)
            .observeOn(AndroidSchedulers.mainThread())
            .subscribeOn(Schedulers.io())
            .subscribe({ result ->
                // Need to be looking for a 204 here.
            if (result != null) {
                Log.d("RR:", "Result ${result}")
                successHandler()
            }
            Log.d(MainActivity.TAG, "*** Success  ***")

            }, {
                // Error null pointer exception comes from it is a 204, empty response.
                // java.lang.NullPointerException: Null is not a valid element
                error ->
                Log.d(MainActivity.TAG, "Error: ${error}")
                error.printStackTrace()
                errorHandler()
            })
            )

        } else {
            Log.d(TAG, "*** NO TOKEN ***")
        }

    }