You are reading an unmaintained version of the Ansible community documentation. Unmaintained Ansible versions can contain security vulnerabilities (CVEs). Please upgrade to a maintained version. See the latest Ansible documentation. Note that this statement does not apply to Red Hat Ansible Automation Platform subscriptions. See the Ansible Automation Platform Life Cycle.
The ansible.builtin.path_join filter has been added in ansible-base 2.10. Community.general 3.0.0 and newer contains an alias community.general.path_join for this filter that could be used on Ansible 2.9 as well. Since community.general no longer supports Ansible 2.9, this is now a simple redirect to ansible.builtin.path_join filter.