It seems that there are a couple of tricks needed to get a manual setup of multiple DataSources working nicely including the externalization of properties. Ideally the sample would show:

1. How to structure properties so that each DataSource has its own distinct configuration.
2. Show how to declare @Bean methods to that they pick up the configuration from the declared property sets.
3. Optionally (if possible and recommended), show how to share some of the properties declared (e.g. user and password) to avoid mistakes when configuration changes.