BAU: Fix currently broken external links

- The Oracle JDK licence page does not resolve outside of a browser
- The FeatureFlags.io article is gone, replace it with a page sourced from Martin Fowler's site
- Minifycode.com is gone, replace it with a link to Google's web dev perf advice
- Replace NIST publication about least privilege with similar page from NCSC

source/manuals/programming-languages/java.html.md.erb

@@ -199,7 +199,7 @@ If you are starting a new Java project, do not use anything older than the lates
 
 If you are currently using an older LTS version of Java, you should be planning to upgrade to something newer. Different Java vendors have different support lifecycles for different Java releases.
 
-Recent versions of the [Oracle JDK can be used free of charge](https://blogs.oracle.com/java/post/free-java-license) for commercial and production purposes under the terms of a bespoke licence. OpenJDK is open source under the [GPLv2 with the Classpath Exception](https://openjdk.java.net/legal/gplv2+ce.html) but Oracle only provide general-availability [OpenJDK builds](https://jdk.java.net/) for the latest release.
+Recent versions of the [Oracle JDK can be used free of charge](https://www.oracle.com/downloads/licenses/no-fee-license.html) for commercial and production purposes under the terms of a bespoke licence. OpenJDK is open source under the [GPLv2 with the Classpath Exception](https://openjdk.java.net/legal/gplv2+ce.html) but Oracle only provide general-availability [OpenJDK builds](https://jdk.java.net/) for the latest release.
 
 The [Adoptium](https://adoptium.net/) (formerly AdoptOpenJDK) project (part of the [Eclipse Foundation](https://www.eclipse.org/)) provides fully open-source TCK-certified pre-built OpenJDK binaries under the name Eclipse Temurin. For LTS releases (such as Java 8, 11 and 17), Adoptium have committed to releasing free updates for several years.
 

source/standards/continuous-delivery.html.md.erb

@@ -64,7 +64,7 @@ Find out more about continuous delivery from:
 - [Trunk Based Development][] - a source control branching method
 
 [Continuous delivery]: https://www.continuousdelivery.com
-[feature-flagging]: https://featureflags.io/2016/10/28/continuous-delivery-coding-patterns-feature-toggles/
+[feature-flagging]: https://martinfowler.com/articles/feature-toggles.html
 [modular architectures]: https://continuousdelivery.com/implementing/architecture/
 [production monitoring and alerting]: https://gds-way.cloudapps.digital/standards/monitoring.html
 [Pull Requests]: https://gds-way.cloudapps.digital/standards/pull-requests.html

source/standards/optimise-frontend-perf.html.md.erb

@@ -18,7 +18,7 @@ For example:
 |---|---|---|
 |#High|Position styles correctly|Set styles at the top of the page and `defer` scripts |
 ||Minimise HTTP requests|Minimise tiling icons, CSS and JavaScript files to reduce size and loading time [HTTP/1.1 only]|
-||Compress static resources|Use [minification][], [Gzip][], and [Brotli][] to compress CSS and JavaScript code|
+||Compress static resources|Use minification, [Gzip][], and [Brotli][] to compress CSS and JavaScript code|
 ||Set correct Headers|Set correct [Cache-Control][] and [ETag][] headers on assets for optimal caching|
 |#Medium|Look for empty image `src` attributes|Avoid using empty image `src` attributes as some browsers always send requests to them, resulting in additional traffic|
 ||Include `width` and `height` attributes on images to minimise layout thrashing | Make sure to include these attributes to improve visual stability and the [Cumulative Layout Shift (CLS)][] metric
@@ -96,7 +96,7 @@ You can find out more about improving your website’s frontend performance by r
 The Service Manual has more suggestions about [how you can test frontend performance][].
 
 [frontend performance]: https://www.gov.uk/service-manual/technology/how-to-test-frontend-performance
-[minification]: https://minifycode.com/
+[minification]: https://web.dev/reduce-network-payloads-using-text-compression/
 [Gzip]: https://web.dev/optimizing-content-efficiency-optimize-encoding-and-transfer/#text_compression_with_gzip
 [Cache-Control]: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control
 [ETag]: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/ETag

source/standards/principle-least-access.html.md.erb

@@ -43,6 +43,6 @@ If you’re using the gds-users account to log into your AWS accounts, you shoul
 
 - [NCSC - 10 steps to cyber security](https://www.ncsc.gov.uk/collection/10-steps)
 - [NCSC - privileged user management](https://www.ncsc.gov.uk/guidance/introduction-identity-and-access-management#section_6)
-- [NIST Special Publication 800-53 - AC-6 least privilege][polp]
+- [NCSC - preventing lateral movement][polp]
 
-[polp]: https://csrc.nist.gov/Projects/risk-management/sp800-53-controls/release-search#!/control?version=5.1&number=AC-6
+[polp]: https://www.ncsc.gov.uk/guidance/preventing-lateral-movement