ArrayList<ModelContact> listContact = new ArrayList<>();

    ModelContact c = new ModelContact("5", "OFF", "Test", "12134567", "14646", "email@email.com", "Adress");
    listContact.add(c);
    c = new ModelContact("6", "ON", "Test2", "12123456", "14646", "email@email.com", "Adress");
    listContact.add(c);

Call<List<ModelContact>> callM = contactInterface.createRContact(listContact);
callM.enqueue(new Callback<List<ModelContact>>() {
    @Override

public void onResponse(Response<List<ModelContact>> response, Retrofit retrofit) {
        Log.i("TAG", "Success");
    }

    @Override
    public void onFailure(Throwable t) {
        Log.i("TAG", "Error: " + t.getMessage());
    }
});

public interface ContactInterface {

    @GET("recieve")
    Call<List<ModelContact>> getRContact();

    @POST("send")
    Call<List<ModelContact>> createRContact(@Body ArrayList<ModelContact> modelContact);}