Uasset importlist and blueprints

I was having a look at cooked uasset files and I noticed the header seems to contain an FObjectExport list and an FObjectImport list which basically references all the other assets this asset needs to work. Typically an uasset for a material will reference textures assets in its FObjectImport list because it needs to import the data from the textures for the material to work properly.

Now, when it comes to blueprints, what exactly makes them being referenced in another uasset’s importlist once cooked? I created several blueprints for a skeletal mesh, and the mesh’s uasset never lists my blueprints in its FObjectImport list section.

More generally, what makes any type of asset being tagged as “needs to be imported” by another asset?

Thank you for your help