Unclear examples for jira:customFieldType module

Hello there,

I am confused about jira:customFieldType module. Object data type seems a valid type:

In the properties section, there are also some requirements for Object type as well.

However, when I try to use it as a type, forge gives an error about invalid type usage.

Another thing that is confusing is examples. In all the examples, for example Object Type JQL Search Example jira:customField module is being used.
image

I don’t understand how to use them together? Should I use them together?

Kind regards,