Retrofit2 - Sending Array of Type T in a GET request

I need to send an array of type User[] in the body of a GET request using retrofit2. This is what the final payload must look like:

body: {
  "data_id": 1,
  "data_provider": "string_value",
  "users": [
    {
      user_id: 1,
      name: 'name'
    },
    {
      user_id: 1,
      name: 'name'
    },
    ...
  ]
}

Current API implementation looks like this:

@GET("api/users/submit.json")
Call<UserData> submitData(@Query("data_id") int data_id, @Query("data_provider") String data_provider, @Query("users[]") User[] users);

Arraylist code:

//Converting the ArrayList<User> usersList to an array
User[] userArray = usersList.toArray(new User[0]);
//The userArray is passed to the retrofit API along with the other request values (data_id, data_provider)

Upon logging the retrofit request, data_id and data_provider are correctly sent except for the User array. The user array looks like this:

api/users/submit.json?data_id=1&data_provider=test&users[]=com.testapp.models.User@7d57487

How can I send an array of type User in the GET request body?