message: style(schema): add comment on why an line is necessary
diff: @@ -94,6 +94,7 @@ export function _buildSchema<U extends AnyParamConstructor<any>>(
  const discriminatorKey = childSch.get('discriminatorKey');
  if (childSch.path(discriminatorKey)) {
  + // skip this check, otherwise "extends DiscriminatorBase" would not be allowed (discriminators cannot have the discriminator key defined multiple times)
  (childSch.paths[discriminatorKey] as any).options.$skipDiscriminatorCheck = true;
  }
  