where com.test.plugin.ui.view.MyView is the id of the view where I want my
command to be shown and com.test.plugin..sdk.Person is the class of the
object (like object contribution).
I want the command to be shown when I right clic on Person in MyView, but
with this description, the command doesn't appear in MyView and appears
disabled in another view wherever I clic (though in my command handler,
isEnabled() method returns true.