json doesnt show hindi text

Question

I have the following User classin my android app

public class User {

@SerializedName("activity_name")
@Expose
private String activityName;
@SerializedName("id")
@Expose
private Integer id;
@SerializedName("image_url")
@Expose
private String imageUrl;
@SerializedName("album_name_hindi")
@Expose
private String albumNameHindi;
@SerializedName("album_name_english")
@Expose
private String albumNameEnglish;

public String getActivityName() {
    return activityName;
}

public void setActivityName(String activityName) {
    this.activityName = activityName;
}

public Integer getId() {
    return id;
}

public void setId(Integer id) {
    this.id = id;
}

public String getImageUrl() {
    return imageUrl;
}

public void setImageUrl(String imageUrl) {
    this.imageUrl = imageUrl;
}

public String getAlbumNameHindi() {
    return albumNameHindi;
}

public void setAlbumNameHindi(String albumNameHindi) {
    this.albumNameHindi = albumNameHindi;
}

public String getAlbumNameEnglish() {
    return albumNameEnglish;
}

public void setAlbumNameEnglish(String albumNameEnglish) {
    this.albumNameEnglish = albumNameEnglish;
}

}

the following is my json code (shortened for the sake of SO)

[
 {
  "activity_name":"Dhamma Jaagran",
  "id":1,
  "image_url":"http://humipack.in/Dj/album01.webp",
  "album_name_hindi":"मंगल स्तुति",
  "album_name_english":"Mangal Stuti"
 },
 {
  "activity_name":"Dhamma Jaagran",
  "id":2,
  "image_url":"http://humipack.in/Dj/album2.webp",
  "album_name_hindi":"भिक्षु स्तुति",
  "album_name_english":"Bhikshu Stuti"
 }
]

The problem i face is i am unable to get the HINDI text properly.. I have saved the Json in UTF-8 format..

I am getting the output for मंगल स्तुति as some random characters mostly seen in Character Map in Windows.. but not in hindi.. Is there any line of code i am missing , for e.g to convert HINDI text to Unicode or UTF-8..

I also refered here but it shows how to make changes in php which i am not using..

What modification do i have to make in my code to get the HINDI in my android app data of which comes from json file..