Retrofit 2. Why is there an error returning the query result?

Question

Java

Guys, I have not been able to fix the error for many days, so I decided to write to the forum in the hope of helping, because. always visible from the outside.
I use Retrofit 2 to work with a bank service to get currency data. I describe an interface where there are 2 methods: one without parameters (data for the current day) and one with a parameter (data for any date).

public interface ApiService {
    @GET("statdirectory/exchange?date=20170916&json")
    Call<List<MyModel>> getСurrency();

    @GET("statdirectory/exchange{date}&json")
    Call<List<MyModel>>  getСurrency(@Path("date") String inputDate);
}

...and call the methods one by one.

ApiService apiService = RetrofitController.getApi();
       // Здесь вызываю метод без параметров и результат возвращается без ошибок, т.е. УСПЕШНО!
       apiService.getCurrency().enqueue(new Callback<List<MyModel>>() {

            @Override
            public void onResponse(Call<List<MyModel>> call, Response<List<MyModel>> response) {
                 if (response.isSuccessful()) {
                    Toast.makeText(MainActivity.this, "УСПЕШНО",  Toast.LENGTH_SHORT).show();
                } else {
                    Toast.makeText(MainActivity.this, "ОШИБКА",  Toast.LENGTH_SHORT).show();
                }
            }
....

When I call the method with the getCurrency("20170916") parameter , an ERROR occurs!
The question is why? I sin on the query string, but, as for me, it's okay, because in theory, the string "statdirectory/exchange{date}&json" will turn into the form "statdirectory/exchange?date=20170916&json" .
Please tell me what could be the problem. Thank you.

Answer 1

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