How to inherit baseURL variable in assertions?

Hello,

I'm trying SoapUI Pro for the moment.

I have 3 platforms where I want to run my tests on

Dev, Test and Stage.

Each has a base URL.

At service level I defined 3 endpoints. dev, test and stage
On project level I defined 3 environments dev, test and stage
Each environment got its own endpoint

When I execute a get on a resource, the response contains links to other resources.
Those resources contain the same baseURL coupled to the environment

I cannot assert this statically, since the baseURL changes when a different environment is selected.
How is the baseURL exposed in the project, and how can I use this in message assertions?
I read about the property expansion
There is a reference to #env# referring to a environment variable

But it is not clear to me, how I can discover what is the current variable for my baseURL's

Can somebody help me out with this question, please?