Steps to reproduce

1. Create a site definition that supports English (en) as default and Welsh (cy) as a secondary language.
2. Use the message bundles to translate a label within a Freemarker template.
3. eg. You will have message bundles my-module-messages_en.properties and my-module-messages_cy.properties and will use the template as documented.

Expected results

When switching between requested languages, the translated label will change from English to Welsh.

Actual results

The Welsh translation appears everywhere, never the English.

Workaround

TBC

Development notes

The DefaultMessageBundlesLoader is, via the LocaleUtils, using the default locales available from the JVM.