[Change Proposal] Resolve use of unspecified fields in the integrations packages field description files

[efd6]

During work on an ECS and pipeline description analysis tool I found that a variety of fields used in integration package field descriptions are not specified. After discussion with @andrewkroh on what to do with these we decided to file this catch-all issue for either letting teams remove the fields and/or for people to have a discussion here to resolve the specification of the fields.

The list is long so it is available at this gist.

The code used to generate the list is here. The output can be regenerated for any commit by checking out the commit and running the code in the packages directory of the github.com/elastic/integrations repo.

[andrewkroh]

My proposal is to enhance the package-spec definition for the fields.yml files with the properties that Fleet EPM actually uses. Those can be found at:

https://github.com/elastic/kibana/blob/b4b3285643dd9105e4c34883e8c032e771ee5fcb/x-pack/plugins/fleet/server/services/epm/fields/field.ts#L14-L59

Of the properties that are already declared, title and dimension are unused. dimension is new in #236 so I assume support will be added to EPM soon. But I'm not sure where title is used.