[CONFIGURATION-831] Unresolved (non-existend) environment variables should return null

• Type: New Feature
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 2.9.0
• Component/s: Interpolation
• Assignee: Unassigned
• Reporter: Wojtek
• Created: 23/May/23 22:16
• Updated: 24/Apr/24 20:20

Description

Currently Interpolation of environment variables (https://commons.apache.org/proper/commons-configuration/userguide/howto_basicfeatures.html#Variable_Interpolation) return un-interpolated string if the environment variable doesn't exists at all.

It would be very convenient and (I feel) more consistent if, in that case, 'null' would be returned.

 

Alternatively, option to specify default if the variable doesn't exist would also work.

I.e. something along the lines:

```

${env:JAVA_HOME:<default value>}

```

 

From my experiments, even if we try to register custom interpolator it's not possible to explicitly return `null` from it.