The "Parameters" field of the "Grouper" element has incorrect behavior in case of "Show/hide"

The "Grouper" element has it's own "Parameters" widget on the "Property Editor" and doesn't have the usual "name-value" table.

Scenario:

1. Open WD
2. Add the "Grouper" element to the scene
3. Click "-" near "Parameters" on the "Property Editor"
   Expected result: the "Parameters" widget is hidden, free space from this widget is squashed
   Current result: the "Parameters" widget is hidden, but there is a lot of free space between "Parameters" and "Input data"
4. Click "+" near "Parameters" on the "Property Editor"
   Expected result: the "Parameters" widget is shown only
   Current result: there are two widgets are shown - the unexpected "name-value" table and "the "Grouper" parameters widget