check duplicate keys

[fugerit79]

Sometimes happen that the same config name is found multiple time in the same config source.

For instance :

quarkus.bannner.enabled=false
quarkus.bannner.enabled=true

Or

quarkus:
  banner:
    enabled: false
  banner:
    enabled: true

In our quarkus projects (whose configuration is based on smallrye-config) this is just silently ignored.

I know that IDE helps avoiding it and developers should be disciplined when writing configuration, but in our large teams sometimes this happened.

But for a Developer Joy approach, it could be helpful to have an Out Of The Box solution.

For instance we could enable duplicate keys check with a system property like ?

smallrye.config.forbidDuplicateKeys