Input Parameter in WebADI, defaults value from Parameter definition value set instead of being NULL

Hi All,

The requirement is to use webADI, to update Grade step of employees. The process we have designed is to download the list of employee details based on certain optional input parameters(Grade, Grade step, Org, Job etc.,). and then the user to enter new Grade, Grade Step , this will then be uploaded using standard API.

After defining the parameter definitions , We are facing an issue with the input parameters, the parameters are coming with default value i.e the first row returned by the Valueset query.  The requirement is to keep these fields NULL(Black) unless the user selects a value from the dropdown list.  I have checked the parameter definition and other options Still no solution found,