在App Sync Resolver中按照时间戳升序排序，可以使用Java中的Comparator接口来实现。以下是一个示例代码：

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

public class AppSyncResolverExample {
    public static void main(String[] args) {
        // 创建一个包含App Sync Resolver的列表
        List resolvers = new ArrayList<>();
        resolvers.add(new AppSyncResolver(2, "Resolver 2", 1000));
        resolvers.add(new AppSyncResolver(1, "Resolver 1", 2000));
        resolvers.add(new AppSyncResolver(3, "Resolver 3", 500));

        // 使用Comparator接口按照时间戳升序排序
        Collections.sort(resolvers, new Comparator() {
            @Override
            public int compare(AppSyncResolver resolver1, AppSyncResolver resolver2) {
                return Long.compare(resolver1.getTimestamp(), resolver2.getTimestamp());
            }
        });

        // 打印排序后的结果
        for (AppSyncResolver resolver : resolvers) {
            System.out.println(resolver);
        }
    }
}

class AppSyncResolver {
    private int id;
    private String name;
    private long timestamp;

    public AppSyncResolver(int id, String name, long timestamp) {
        this.id = id;
        this.name = name;
        this.timestamp = timestamp;
    }

    public int getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public long getTimestamp() {
        return timestamp;
    }

    @Override
    public String toString() {
        return "AppSyncResolver{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", timestamp=" + timestamp +
                '}';
    }
}

在上述示例中，我们定义了一个AppSyncResolver类，该类包含了一个时间戳属性。然后，我们创建了一个包含AppSyncResolver对象的列表，并使用Collections.sort方法和自定义的Comparator接口来按照时间戳升序排序。最后，我们打印排序后的结果。

请注意，这只是一个示例代码，你可以根据你的实际需求进行适当的修改。