* Remove usage of removed `org.springframework.util.SocketUtils`
in favor of OS-selected port
* Migrate mail tests to Greenmail instead of already obsolete (and soon to be removed)
`org.springframework.integration.test.mail.TestMailServer`
This commit updates URLs to prefer the https protocol. Redirects are not followed to avoid accidentally expanding intentionally shortened URLs (i.e. if using a URL shortener).
# Fixed URLs
## Fixed Success
These URLs were switched to an https URL with a 2xx status. While the status was successful, your review is still recommended.
* [ ] http://www.apache.org/licenses/LICENSE-2.0 with 300 occurrences migrated to:
https://www.apache.org/licenses/LICENSE-2.0 ([https](https://www.apache.org/licenses/LICENSE-2.0) result 200).
