public Inspector()

{
  // Loads a feature from the specified feature layer into an Inspector instance.
  // create an instance of the inspector class
  var inspector = new Inspector();
  // load the feature with ObjectID 'objectId' into the inspector
  await inspector.LoadAsync(featureLayer, objectId);
}

// Adds a custom validation rule to the "Mineral" field of the specified feature layer.
await QueuedTask.Run(() =>
{
  var insp = new Inspector();
  insp.LoadSchema(featureLayer);
  var attrib = insp.Where(a => a.FieldName == "Mineral").First();
  attrib.AddValidate(() =>
  {
    if (attrib.CurrentValue.ToString() == "Salt")
      return [];
    else return [ArcGIS.Desktop.Editing.Attributes.Attribute.ValidationError.Create("Error", Severity.Low)];
  });
});