I am not much active on the tool these days. So, dont have the latest version as well. Any ways, the screen shot attached by the author of this original post is not helpful. It would be helpful if the details are provided along with the sample response (resembling exact structure, need not be the original response) .
I think I got part of the issue. Need ti investigate more but I'll be on vacation soon.
I wrote the following :
1/ I call WS1 and gets param1 value in the response
2/ I call WS2 which uses as input the value of param1
The issue is that when param1 is empty, it is actually set as "null" in the input of WS2 (this input is not a mandatory parameter)
I was mistaken by the "outline" tab of the response. it shows an empty value for param1. But if I look like in the JSON tab, I see "param1" : null,
I focused on the "outline" tab content, which made me think the value was an empty string. A,d therefore could not understand why this emty string was transalted into a "null" value when reused later on. But in fact, it reused the correct value. It is what is displayed in the "outline" tab which is misleading.
See attached screen captures which are both extract of the same WS response.