vCO workflow "Get IP from FQDN" executed successfully, but returns null string

I am using vCO plugin for F5(Version 2.0).

I want to fetch IP address from FQDN. Workflow is available in 'F5 Networks' package named "Get IP from FQDN" under LTM folder.

When I start the workflow, it will ask for iControlLocalLB object and FQDN. After entering input, workflow executed successfully. But output string is null. Is anything missing from me(DNS entry etc.) during configuration?

Actually, I didn't get the purpose of the workflow. Whether it's purpose is to resolve host-name? If yes, why it is taking iControlLocalLB object as input? Because, I can do same task using vCO API System.resolveHostName(...).