After upgrading the Active Choice Parameter plugin from 2.6.5 to the latest, parameters that used referenced parameter with null values end up being null.

How to Reproduce

• Create a parameterized pipeline with the following parameters:
• An Active Choice Parameter param1 with the following groovy script:

def param1 = null
return [param1]

• An Active Choice Reactive Parameter param2 with param1 as *Referenced Parameters* the following groovy script:

def param2 = param1 + 'test'
return [param2]

• Hit build with parameters

--> param1 shows an empty list (expected)
--> param2 shows an empty list (un-expected)

Rather, this was working before, with version 2.6.5 of the plugin and 2.387.3 of core. But the behavior changed after upgrading to current latest 2.8.3 and core 2.440.3.