[Credentials Cache PR4]Add dynamic advisory refresh window and update prefetch behavior

[alextwoods]

This PR merges to feature/master/credential_cache, NOT to master
[Credential Cache Pr 4].

Updates based on updates to cross-sdk spec

Modifications

1. Dynamic advisory refresh window: When the user has NOT explicitly configured a prefetchTime, compute the advisory window dynamically based on the credential's remaining lifetime:

   • remaining < 20 min -> 5 min window
   • 20 min <= remaining < 90 min -> 15 min window
   • remaining >= 90 min -> 60 min window This is recomputed on each successful refresh. If the user HAS explicitly configured a value, it is always honored unchanged.

2. Prefetch failure stale time preservation: When a credential refresh fails during the advisory (prefetch) window, extend the prefetch time by backoff but preserve the existing stale time if it is later than the new prefetch time. Previously both were set to the same backoff value, which could move the mandatory refresh boundary closer than intended.

3. Treat failures to read the cached token from disk as invalidating/terminal failures and skip static stability on refresh (ie, immediately raise the error prompting user to re-authenticate).

Testing

New and existing tests.

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Checklist

• I have read the CONTRIBUTING document
• Local run of mvn install succeeds
• My code follows the code style of this project
• My change requires a change to the Javadoc documentation
• I have updated the Javadoc documentation accordingly
• I have added tests to cover my changes
• All new and existing tests passed
• I have added a changelog entry. Adding a new entry must be accomplished by running the scripts/new-change script and following the instructions. Commit the new file created by the script in .changes/next-release with your changes.

License

• I confirm that this pull request can be released under the Apache 2 license

[dagnir]

I was going to suggest FieldWithDefault but I didn't realize it's internal to s3 😅

aws-sdk-java-v2/services/s3/src/main/java/software/amazon/awssdk/services/s3/internal/FieldWithDefault.java

Lines 29 to 32 in bb23595

	@SdkInternalApi
	public abstract class FieldWithDefault<T> {
	private FieldWithDefault() {
	}

Given how many places this occurs, would it make sense to add a version of this class to utils?

[alextwoods]

I've actually cleaned this up a slightly diffrent way - since there isn't actually a default here, its more - use the value if set, otherwise compute it from the expiration. We now just check if the prefetchTime is null (ie, unset) and if so, compute the value from the expiration.

[github-actions]

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