[8.6.0] Classify UnknownHostException as retriable for repository

[bazel-io]

UnknownHostException can represent a transient failure in DNS.
Permit this exception to trigger the retry logic for the download loop.

Closes #28023.

PiperOrigin-RevId: 854154072
Change-Id: I84bca74b00af1bbbb322ecc3f8697ed252dbfe64

Commit 8fe8d55

[gemini-code-assist]

Code Review

The pull request aims to classify UnknownHostException as a transient failure to trigger retry logic. While DownloadManager.java correctly adds UnknownHostException to its retryable exceptions, HttpConnector.java wraps this exception in an UnrecoverableHttpException. This counteracts the intended retry mechanism, as UnrecoverableHttpException is not considered retryable by the DownloadManager. This inconsistency needs to be resolved to ensure the retry logic functions as intended.

[gemini-code-assist]

This change wraps UnknownHostException in an UnrecoverableHttpException. However, the PR description states that UnknownHostException should trigger retry logic, and DownloadManager.java has been updated to consider UnknownHostException as retryable. By wrapping it in UnrecoverableHttpException, the DownloadManager will not retry, as UnrecoverableHttpException is not listed as a retryable exception. This contradicts the stated goal of the pull request. To enable retries for UnknownHostException, it should either be re-thrown directly or wrapped in an exception that DownloadManager recognizes as retryable.

Suggested change

	IOException httpException = new UnrecoverableHttpException(message);
	httpException.addSuppressed(e);
	throw httpException;
	throw e;