title: Unable to create converter for my class in Android Retrofit library
body: <p>Im migrating from using Volley to Retrofit, I already have gson class that I used before for converting JSONObject reponse to a object that implements gson annotations. When I'm trying to make http get request using retrofit but then my app crashes with this error :</p>
  
  <pre><code> Unable to start activity ComponentInfo{com.lightbulb.pawesome/com.example.sample.retrofit.SampleActivity}: java.lang.IllegalArgumentException: Unable to create converter for class com.lightbulb.pawesome.model.Pet
      for method GitHubService.getResponse
  </code></pre>
  
  <p>Im following the guide in <a href="http://square.github.io/retrofit/">retrofit</a> site and I come up with these implementations :</p>
  
  <p>This is my activity where I am trying to execute the retro http request:</p>
  
  <pre><code>public class SampleActivity extends AppCompatActivity {
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_sample);
  
          Retrofit retrofit = new Retrofit.Builder()
                  .baseUrl("**sample base url here**")
                  .build();
  
          GitHubService service = retrofit.create(GitHubService.class);
          Call&lt;Pet&gt; callPet = service.getResponse("41", "40");
          callPet.enqueue(new Callback&lt;Pet&gt;() {
              @Override
              public void onResponse(Response&lt;Pet&gt; response) {
                  Log.i("Response", response.toString());
              }
  
              @Override
              public void onFailure(Throwable t) {
                  Log.i("Failure", t.toString());
              }
          });
          try{
              callPet.execute();
          } catch (IOException e){
              e.printStackTrace();
          }
  
      }
  }
  </code></pre>
  
  <p>My interface which turned to be my API</p>
  
  <pre><code>public interface GitHubService {
      @GET("/ **sample here** /{petId}/{otherPet}")
      Call&lt;Pet&gt; getResponse(@Path("petId") String userId, @Path("otherPet") String otherPet);
  }
  </code></pre>
  
  <p>And finally the Pet class which should be the reponse:</p>
  
  <pre><code>public class Pet implements Parcelable {
  
      public static final String ACTIVE = "1";
      public static final String NOT_ACTIVE = "0";
  
      @SerializedName("is_active")
      @Expose
      private String isActive;
      @SerializedName("pet_id")
      @Expose
      private String petId;
      @Expose
      private String name;
      @Expose
      private String gender;
      @Expose
      private String age;
      @Expose
      private String breed;
      @SerializedName("profile_picture")
      @Expose
      private String profilePicture;
      @SerializedName("confirmation_status")
      @Expose
      private String confirmationStatus;
  
      /**
       *
       * @return
       * The confirmationStatus
       */
      public String getConfirmationStatus() {
          return confirmationStatus;
      }
  
      /**
       *
       * @param confirmationStatus
       * The confirmation_status
       */
      public void setConfirmationStatus(String confirmationStatus) {
          this.confirmationStatus = confirmationStatus;
      }
  
      /**
       *
       * @return
       * The isActive
       */
      public String getIsActive() {
          return isActive;
      }
  
      /**
       *
       * @param isActive
       * The is_active
       */
      public void setIsActive(String isActive) {
          this.isActive = isActive;
      }
  
      /**
       *
       * @return
       * The petId
       */
      public String getPetId() {
          return petId;
      }
  
      /**
       *
       * @param petId
       * The pet_id
       */
      public void setPetId(String petId) {
          this.petId = petId;
      }
  
      /**
       *
       * @return
       * The name
       */
      public String getName() {
          return name;
      }
  
      /**
       *
       * @param name
       * The name
       */
      public void setName(String name) {
          this.name = name;
      }
  
      /**
       *
       * @return
       * The gender
       */
      public String getGender() {
          return gender;
      }
  
      /**
       *
       * @param gender
       * The gender
       */
      public void setGender(String gender) {
          this.gender = gender;
      }
  
      /**
       *
       * @return
       * The age
       */
      public String getAge() {
          return age;
      }
  
      /**
       *
       * @param age
       * The age
       */
      public void setAge(String age) {
          this.age = age;
      }
  
      /**
       *
       * @return
       * The breed
       */
      public String getBreed() {
          return breed;
      }
  
      /**
       *
       * @param breed
       * The breed
       */
      public void setBreed(String breed) {
          this.breed = breed;
      }
  
      /**
       *
       * @return
       * The profilePicture
       */
      public String getProfilePicture() {
          return profilePicture;
      }
  
      /**
       *
       * @param profilePicture
       * The profile_picture
       */
      public void setProfilePicture(String profilePicture) {
          this.profilePicture = profilePicture;
      }
  
  
      protected Pet(Parcel in) {
          isActive = in.readString();
          petId = in.readString();
          name = in.readString();
          gender = in.readString();
          age = in.readString();
          breed = in.readString();
          profilePicture = in.readString();
      }
  
      @Override
      public int describeContents() {
          return 0;
      }
  
      @Override
      public void writeToParcel(Parcel dest, int flags) {
          dest.writeString(isActive);
          dest.writeString(petId);
          dest.writeString(name);
          dest.writeString(gender);
          dest.writeString(age);
          dest.writeString(breed);
          dest.writeString(profilePicture);
      }
  
      @SuppressWarnings("unused")
      public static final Parcelable.Creator&lt;Pet&gt; CREATOR = new Parcelable.Creator&lt;Pet&gt;() {
          @Override
          public Pet createFromParcel(Parcel in) {
              return new Pet(in);
          }
  
          @Override
          public Pet[] newArray(int size) {
              return new Pet[size];
          }
      };
  }
  </code></pre>