List FieldRef (Ref to Site Column) won't be exported if this list enabled content type management and this field is not visible on list content types

[wuxiaojun514]

I found an interesting problem when run Export-PnPListToSiteTemplate command.

My Scenario

Let me describe my scenario first.

I have one list which enabled content type management, because I have two content types under this list

Some of the list fields are site column

And these two site columns are set as hidden in my list content type

Missing site column field ref in the exported template

Then it (those two site column field ref) won't get exported when I run Export-PnPListToSiteTemplate or other export template command.
In this case it only exported "Title" since "Tifle" field is visible in list content type

However if I disable the content type management on the list, then I can get all site columns used in this list.

In the source code https://github.com/pnp/pnpframework/blob/dev/src/lib/PnP.Framework/Provisioning/ObjectHandlers/ObjectListInstance.cs#L2776, it will not add hidden site column as field ref if the list enabled content type

  if (siteList.ContentTypesEnabled && contentTypeFields.FirstOrDefault(c => c.Id == field.Id) == null)
                    {
                        if (contentTypeFields.FirstOrDefault(c => c.Id == field.Id) == null)
                        {
                            addField = false;
                        }
                    }

[wuxiaojun514]

I am not very clear why we put this logic to stop export site column field ref when enabled content type, but obviously the Invoke-PnPSiteTemplate will fail if pnp:FieldRef missing.

I can try to raise a pr for it.