GSON's JsonAdapter for handle `{ @nil:true }` in tranfromed JSON from XML

Nillable.java

import com.google.gson.JsonDeserializationContext;
import com.google.gson.JsonDeserializer;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParseException;
import java.lang.reflect.Type;

class Nillable<T> implements JsonDeserializer<T> {

  @Override
  public T deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context)
    throws JsonParseException
  {
    if (json.isJsonObject()) {
      JsonObject object = json.getAsJsonObject();
      if (object.has("@nil")) {
        return null;
      }
    }
    return context.deserialize(json, typeOfT);
  }
}