Hi all, I'm trying to deserialize a Json string into a custom class

public class Artist
{
    public Artist()
    {
        this.Albums = new ArrayList<Album>();
    }

    @SerializedName("artist")
    String Artist;

    @SerializedName("id")
    String ID;

    @Expose
    ArrayList<Album> Albums = null;
    

    @Expose
	String PlaceHolder = "";
    }

The problem I'm having is only the fields that are present in the Json string (id and artist ) are getting deserialized, what I want is for the other properties to be set to null which I will populate later. Any ideas ?