/usr/share/php/Icinga/Web/Navigation/ is in php-icinga 2.1.0-1ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/php/Icinga/Web/Navigation/DashboardPane.php
/usr/share/php/Icinga/Web/Navigation/DropdownItem.php
/usr/share/php/Icinga/Web/Navigation/Navigation.php
/usr/share/php/Icinga/Web/Navigation/NavigationItem.php
/usr/share/php/Icinga/Web/Navigation/Renderer/
/usr/share/php/Icinga/Web/Navigation/Renderer/BadgeNavigationItemRenderer.php
/usr/share/php/Icinga/Web/Navigation/Renderer/NavigationItemRenderer.php
/usr/share/php/Icinga/Web/Navigation/Renderer/NavigationRenderer.php
/usr/share/php/Icinga/Web/Navigation/Renderer/NavigationRendererInterface.php
/usr/share/php/Icinga/Web/Navigation/Renderer/RecursiveNavigationRenderer.php
/usr/share/php/Icinga/Web/Navigation/Renderer/SummaryNavigationItemRenderer.php