private static boolean isCreateSupported(DBNNode parentNode, Class<?> objectClass) {
        DBEObjectMaker objectMaker = DBWorkbench.getPlatform().getEditorsRegistry().getObjectManager(objectClass, DBEObjectMaker.class);
        return objectMaker != null && objectMaker.canCreateObject(
            parentNode instanceof DBNDatabaseNode ?
                ((DBNDatabaseNode) parentNode).getValueObject() : parentNode.getOwnerProject());
    }
Sorry, this is a bit over-complicated handler. Historical reasons.
It can create object of specified type (in parameters) or for current selection.
Dynamic menu "Create" fills elements with parameters. Direct contribution of create command will create nearest
object type according to navigator selection.
plugins/org.jkiss.dbeaver.ui.navigator/src/org/jkiss/dbeaver/ui/navigator/actions/NavigatorHandlerObjectCreateNew.java