In 2021, @lacherp has done a nice spy to display all the adapter factories that can adapt a source class in a target class.

This spy is displayed like this :

That would be nice to include this spy in the pde spies collection. It's located here : org.eclipse.e4.tools.adapter.spy

The work to do is to rename this bundle to : org.eclipse.pde.spy.adapter, and to test it it is still working and relevant.