Null fields should not be included in JSON response.

http://localhost:8080/kie-server/services/rest/server/queries/tasks/instances/TaskID

{
  "task-id" : 1,
  "task-priority" : 0,
  "task-name" : "Task",
  "task-subject" : null,
  "task-description" : "",
  "task-type" : null,
  "task-form" : null,
  "task-status" : "Reserved",
  "task-actual-owner" : "bpmsAdmin",
  "task-created-by" : "",
  "task-created-on" : {
  "java.util.Date" : 1587647388243
},
  "task-activation-time" : {
  "java.util.Date" : 1587647388243
},
  "task-expiration-time" : null,
  "task-skippable" : null,
  "task-workitem-id" : 1,
  "task-process-instance-id" : 1,
  "task-parent-id" : null,
  "task-process-id" : "HT.T1",
  "task-container-id" : "HT_1.0.0-SNAPSHOT",
  "sla-compliance" : null,
  "sla-due-date" : null,
  "task-pot-owners" : null,
  "task-excl-owners" : null,
  "task-business-admins" : null,
  "task-input-data" : null,
  "task-output-data" : null
}