This is part of the new domain support recently added to the automate model. The ManageIQ domain is the “base domain” and is the lowest priority (zero) domain. The note in the UI of “(Locked)” indicates that it can not be altered in any way.
You customize the automate model by creating override domains that are processed in descending priority order, so any classes, instances, or methods in a higher domain will override the same elements in the base domain.
There is currently support to manage custom domains and will soon be support for copying elements from one domain to another to make it easier to implement overrides. In addition, custom domains can also be locked by authorized users to prevent changes.