Feature Request - Ability to use Default Values only when no value found

[Christophoclese]

The current behavior, at least with SNMP discovery and properties like Interface Description, appears to always use the default value specified by the policy's defaults. It would be nice to be able to utilize discovered Interface descriptions first and only substitute the default value if the discovered value is null or empty string.

This would probably be true for other properties as well, such as Device Description.