Application with default value and the value can be overwritten

As an operations person, I want to be able to overwrite/tweak certain configuration values which come as part of the application.

Otoh it should not be required to provide every configured value by the ops team. Applications must work out of the box - tweaking configuration values should only be required if really needed.

No files, tests, or entry points are named. Start by reviewing the existing configuration behavior and related project discussions to define how application defaults and operations-provided overrides should interact, then establish tests that show applications work without every value being supplied.

Written by the indexing model from the issue text.