UserService.java

package io.github.wingyplus.retrofittut;

import retrofit2.Call;
import retrofit2.http.GET;
import retrofit2.http.Headers;
import retrofit2.http.Path;

public interface UserService {

  @Headers({
    "Accept: application/vnd.github.v3.full+json",
    "User-Agent: Retrofit-Sample-App"
  })
  @GET("users/{username}")
  Call<User> getSingleUser(@Path("username") String username);
}