1. Improve wording of documentation. Note the concrete object that will be written in its entirety
2. Expand documentation. Note a potential security risk for secrets
3. Move, without changes, the `warnIfNotFound` method because it was putting space between `getValueFromSource` and the various source type specific functions it uses
4. Implement unit tests for `warnIfNotFound`
5. Implement unit tests for `logWarning`