{
    "timestamp": "2018-07-22T17:06:20.111+0000",
    "status": 500,
    "error": "Internal Server Error",
    "message": "E11000 duplicate key error collection: newdb.user index: subscribedTo.username dup key: { : null }; nested exception is com.mongodb.MongoWriteException: E11000 duplicate key error collection: newdb.user index: subscribedTo.username dup key: { : null }",
    "path": "/user/add"
}

@Document(collection = "user")
@Data
public class User{

    @Id
    private String id;

    @Indexed(unique = true)
    @NotBlank
    private String username;

    @NotBlank
    @Size(min=5, max=32)
    private String password;

    @Indexed(unique = true)
    @Email
    private String email;

    @CreatedDate
    private Date dateRegistered;

    @LastModifiedDate
    private Date dateLastEntry;

    private String profilePictureUrl;

    private List<User> subscribedTo;

    private int active; //0 for false

    public User(@NotBlank String username,
                @NotBlank @Size(min = 5, max = 32) String password,
                @Email String email,
                String profilePictureUrl) {
        this.id = UUID.randomUUID().toString();
        this.username = username;
        this.password = password;
        this.email = email;
        this.dateRegistered = new Date();
        this.dateLastEntry = new Date();
        this.profilePictureUrl = profilePictureUrl;
        this.subscribedTo = Arrays.asList();
        this.active = 1;
    }
}