Currently contributions by E4 are not filtered using the E3 activity
mechanism as it is a pure E3 concept.

To improve integration and interaction of E4 and E3 when using the
compatibility layer this now installs a WorkbenchContributionFactory
into the application context that additionally takes activity filtering
of the E3 workbench into account.

See https://github.com/eclipse-platform/eclipse.platform.ui/issues/2217