expected BEGIN_OBJECT but was BEGIN_ARRAY in Retrofit2

I am trying to post this json object with retrofit

{
  "ingredients": [
    {
      "quantity": 1,
      "measureURI": measureUri,
      "foodId": foodId
    }
  ]
}

I succeeded using python:

import requests

APP_ID = "app_id_"
API_KEY = "api_key"
BASE = "https://api.edamam.com/api/food-database/v2/nutrients?"

url = f"https://api.edamam.com/api/food-database/v2/nutrients?app_id={APP_ID}&app_key={API_KEY}"
data = {
        "ingredients": [
            {
                "quantity": 1,
                "measureURI":  "http://www.edamam.com/ontologies/edamam.owl#Measure_unit",
                "foodId":  "food_a1gb9ubb72c7snbuxr3weagwv0dd"
            }
        ]
    }

res = requests.post(url, json=data)
print(res.text) 

But I can not do same with retrofit.
Here is my service interface

@POST(Constants.API_PATH_NUTRIENTS + "?app_id=" + Constants.APP_ID + "&app_key=" + Constants.API_KEY)
Call<NutrientsResponseSchema> getFoodNutrients(@Body NutrientsRequestSchema requestSchema);

And Request schema models

public class NutrientsRequestSchema {
    public List<IngredientsRequestSchema> ingredients;

    public NutrientsRequestSchema(List<IngredientsRequestSchema> ingredients) {
        this.ingredients = ingredients;
    }
}

public class IngredientsRequestSchema {
    public float quantity;
    public String foodId;

    @SerializedName("measureURI")
    public String measureUri;

    public IngredientsRequestSchema(float quantity,
                                    String measureUri,
                                    String foodId) {
        this.quantity = quantity;
        this.measureUri = measureUri;
        this.foodId = foodId;
    }
}

When I run code and request from service I get

>
> com.google.gson.JsonSyntaxException:
> java.lang.IllegalStateException: Expected BEGIN_OBJECT but was
> BEGIN_ARRAY at line 298 column 20 path $.ingredients
>

The error message is clear, you have defined NutrientsResponseSchema such that, you expected ingredients to be an object but the ingredients from server is definitely an array as suggested by

{
  "ingredients": [
    {
      "quantity": 1,
      "measureURI": measureUri,
      "foodId": foodId
    }
  ]
}

ingredients is an array of Ingredient. but in your NutrientsResponseSchema, you must have defined

   @SerializedName("ingredients")
    public Ingredient ingredient; //POJO and not a list of POJO

You can easily fix this by, changing your NutrientsResponseSchema as

   @SerializedName("ingredients")
    public List<Ingredient> ingredients; //List of POJO

EDIT: To explain more:

You have your NutrientsResponseSchema:

public class NutrientsResponseSchema {
    public String uri;
    public float calories;
    public float totalWeight;
    public List<String> dietLabels;
    public List<String> healthLabels;
    public List<String> cautions;
 
    public TotalNutrients totalNutrients;
    public Ingredients ingredients;
}

You need to change your last line to:

public class NutrientsResponseSchema {
    public String uri;
    public float calories;
    public float totalWeight;
    public List<String> dietLabels;
    public List<String> healthLabels;
    public List<String> cautions;
 
    public TotalNutrients totalNutrients;
    @SerializedName("ingredients")
    public List<Ingredient> ingredients;
}

and Ingredient can be:

public class Ingredient{
    public float quantity;
    public String food;
    public String foodId;
    public float weight;
    public float retainedWeight;
    public String measureUri;
    public String status;
}