Regarding Restoration expiration time for multiple files.

To achieve the desired expiration time for all 20 files in your AWS Glacier restoration scenario using the AWS SDK for Java, you can use the RestoreRequest class with specific parameters. Here's how you can approach this:

1. First, you'll need to create a RestoreRequest object for each file you want to restore.

2. When building the RestoreRequest, use the days() method to set the lifetime of the active copy. In your case, you want all files to expire on 26th October 2024 at midnight, which is 3 days from the initial request date (23rd October 2024).

3. You can use the RestoreRequest.Builder to construct your request. Here's an example of how you might set this up:

RestoreRequest restoreRequest = RestoreRequest.builder() .days(3) .glacierJobParameters(GlacierJobParameters.builder() .tier(Tier.STANDARD) .build()) .build();

4. The days(3) method call sets the expiration time to 3 days from when each individual file is restored, regardless of when the restoration actually completes.

5. You would then use this RestoreRequest object when initiating the restore for each of your 20 files.

By setting the expiration to 3 days for all files, you ensure that regardless of when each file's restoration completes, they will all expire at the same time - 3 days from the initial request date, which in this case would be 26th October 2024 at midnight.

Remember that the actual implementation might vary depending on how you're initiating the restore requests (e.g., in parallel or sequentially), but the key is to use the same RestoreRequest object with the 3-day expiration for all files.

This approach ensures that all 20 files will have the same expiration time, regardless of when their individual restorations complete, achieving your goal of having all files expire on 26th October 2024 at midnight.
Sources
RestoreRequest.Builder (AWS SDK for Java - 2.21.29)
RestoreRequest (AWS SDK for Java - 2.21.28)