annotations

There are direct usages of javax.annotations annotations in the code and
what is done here just follows what is already done
o.e.e4.ui.bindings/services, org.eclipse.e4.ui.workbench.addons.swt,
org.eclipse.e4.ui.workbench.renderers.swt and probably others. It was
working previously because PDE resolved javax.annotation from the jvm
(pre Java 11) which can no longer happen so the import-package is needed
for equinox to load javax.annotation bundle.

Change-Id: Id9b689f905cf589d69c2337aff8512210bfd2ed0
Signed-off-by: Alexander Kurtakov <akurtako@redhat.com>