Fix wrong usage of nullable prop next to a ref. TLDR $ref shouldn’t have sibling. (unless OpenAPI 3.1 that allows description and summary only I believe).
This induce wrong api documentation and most importantly bugs in our python clients such as:

• apache/airflow-client-python@ddd6fc0 That needs to be manually cherry picked on each new release.
• Update task_instance.py airflow-client-python#89 another occurence that we forgot to also manually patch post client generation.-

This allows to generate the expected api doc and the correct client.
I Tried that locally by regenerating the client and making the problematic call, such as:

# The one that cancelled 2.6.2rc1 client.
dag_api_instance.get_tasks(DAG_ID)

It is working with this spec.

After this we can:

• Update the client release process to remove the cherry picking part. (manual fix)
• Close Update task_instance.py airflow-client-python#89
• Add a pre-commit hook to prevent siblings on $ref elements. (check why the current spec validator wrongfully allows it)