Currently, the Jenkins API for jobs returns run parameter definitions in the following way (JSON here but the result for XML is equivalent):

{
   "_class":"hudson.model.RunParameterDefinition",
   "defaultParameterValue":{
      "_class":"hudson.model.RunParameterValue"
   },
   "description":"",
   "name":"Run_Parameter",
   "type":"RunParameterDefinition",
   "projectName":"Project"
}

Unfortunately this parameter definition does not include the build filter that can be set up alongside the projectName and description when configuring the run parameter.

I believe that including this filter in the JSON would be beneficial for some use cases while not affecting others. The proposed return value would look like this:

{
   "_class":"hudson.model.RunParameterDefinition",
   "defaultParameterValue":{
      "_class":"hudson.model.RunParameterValue"
   },
   "description":"",
   "name":"Run_Parameter",
   "type":"RunParameterDefinition",
   "filter":"COMPLETED",
   "projectName":"Project"
}

I would be very glad to implement this change myself if the change is agreed upon.

Furthermore, I would be interested in knowing whether there are any ways to circumvent the current behaviour and retrieve the filter nonetheless.