Can you tell me what is the bug in this code and how to fix it?

import java.util.ArrayDeque; import java.util.Queue; public class QueueWrapper { private Queue data; public QueueWrapper() {this.data = new ArrayDeque(); } public boolean enqueue (int i) { return this.data.add(i); } public int dequeue () { return this.data.remove(); public QueueWrapper copy () { QueueWrapper result = new QueueWrapper(); while (!this.data.isEmpty()) { result.enqueue (this.data.remove()); return result