Composer 8.1.4 - Backend Block and additionalParams. How use a Json Object ?

[ymattica]

Hi,
Using a jsp page as an uri in a WebRequest block, I am able to work with an input  json object and use it in java code in my jsp page
Using backend block... can I use a json object too ??
I would like to pass a jason object as an additional parameter.
Setting  'Pass state' = true  on the Backend block , it works ( I am able to get the json object in the jsp )  but I would like to set 'Pass state' = false and pass a json string like an additional parameter.

Regards