Please see attached the screenshot of the errors on the spec file.

The first error is the major one: 

Semantic error at paths./notifications/{id}

Declared path parameter "id" needs to be defined as a path parameter at either the path or operation level.

This causes the creation of the iqe client to fail.
I succeeded to manually fix it locally by adding this part to the spec file on line 174:
parameters:
- name: id
in: path
description: UUID of the notification
required: true
schema:
$ref: '#/components/schemas/UUID'

See screen shot after the fix.