Fixes #36497 - Allow unsetting GPG and SSL keys

[evgeni]

What are the changes introduced in this pull request?

Without allow_nil: true API clients don't know they can update this parameter to nil to unset it again.

Considerations taken when implementing this change?

I want a working API :)

What are the testing steps for this pull request?

Using FAM, run the following playbook:

- name: issue 36497
  hosts: localhost
  become: no
  gather_facts: no
  tasks:
    - name: "create key"
      theforeman.foreman.content_credential:
        username: "admin"
        password: "changeme"
        server_url: "https://foreman.example.com/"
        validate_certs: false
        name: "RPM-GPG-KEY-my-repo"
        content_type: gpg_key
        organization: "Default Organization"
        content: "lol test"
    - name: product with key
      theforeman.foreman.product:
        username: "admin"
        password: "changeme"
        server_url: "https://foreman.example.com/"
        validate_certs: false
        name: "lol prod"
        organization: "Default Organization"
        gpg_key: "RPM-GPG-KEY-my-repo"
    - name: product without key
      theforeman.foreman.product:
        username: "admin"
        password: "changeme"
        server_url: "https://foreman.example.com/"
        validate_certs: false
        name: "lol prod"
        organization: "Default Organization"
        gpg_key: ""

Without the patch, the execution will fail with:

fatal: [localhost]: FAILED! => {"changed": false, "msg": "Error while performing update on products: gpg_key_id can't be None"}

[theforeman-bot]

Issues: #36497

[evgeni]

[test katello]

[jeremylenz]

Before:

vagrant@centos8-katello-devel-stable ~]$ ansible-playbook test_playbook.yml
[WARNING]: provided hosts list is empty, only localhost is available. Note that the implicit localhost does not match 'all'

PLAY [issue 36497] ****************************************************************************************************************************************************************

TASK [create key] *****************************************************************************************************************************************************************
ok: [localhost]

TASK [product with key] ***********************************************************************************************************************************************************
ok: [localhost]

TASK [product without key] ********************************************************************************************************************************************************
fatal: [localhost]: FAILED! => {"changed": false, "msg": "Error while performing update on products: gpg_key_id can't be None"}

PLAY RECAP ************************************************************************************************************************************************************************
localhost                  : ok=2    changed=0    unreachable=0    failed=1    skipped=0    rescued=0    ignored=0   

After:

[vagrant@centos8-katello-devel-stable ~]$ ansible-playbook test_playbook.yml
[WARNING]: provided hosts list is empty, only localhost is available. Note that the implicit localhost does not match 'all'

PLAY [issue 36497] ****************************************************************************************************************************************************************

TASK [create key] *****************************************************************************************************************************************************************
ok: [localhost]

TASK [product with key] ***********************************************************************************************************************************************************
ok: [localhost]

TASK [product without key] ********************************************************************************************************************************************************
changed: [localhost]

PLAY RECAP ************************************************************************************************************************************************************************
localhost                  : ok=3    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0   

thanks @evgeni! ACK 👍