When a linkfield targets an asset it is a common requirement to show a preview of the linked asset, in the form itself.
(Note: A preview in the chooser is nice too - but thats not what this ticket is about.)
IN M5 we had this preview class:
But in M6 there is not yet an equivalent.
Based on these docs, I guess it should implement 'info.magnolia.ui.preview.ItemPreviewComponent'