/usr/share/php/Icinga/Web/Form/ is in php-icinga 2.1.0-1ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/php/Icinga/Web/Form/Decorator/
/usr/share/php/Icinga/Web/Form/Decorator/Autosubmit.php
/usr/share/php/Icinga/Web/Form/Decorator/ConditionalHidden.php
/usr/share/php/Icinga/Web/Form/Decorator/ElementDoubler.php
/usr/share/php/Icinga/Web/Form/Decorator/FormDescriptions.php
/usr/share/php/Icinga/Web/Form/Decorator/FormHints.php
/usr/share/php/Icinga/Web/Form/Decorator/FormNotifications.php
/usr/share/php/Icinga/Web/Form/Decorator/Help.php
/usr/share/php/Icinga/Web/Form/Decorator/Spinner.php
/usr/share/php/Icinga/Web/Form/Element/
/usr/share/php/Icinga/Web/Form/Element/Button.php
/usr/share/php/Icinga/Web/Form/Element/CsrfCounterMeasure.php
/usr/share/php/Icinga/Web/Form/Element/DateTimePicker.php
/usr/share/php/Icinga/Web/Form/Element/Note.php
/usr/share/php/Icinga/Web/Form/Element/Number.php
/usr/share/php/Icinga/Web/Form/Element/TriStateCheckbox.php
/usr/share/php/Icinga/Web/Form/ErrorLabeller.php
/usr/share/php/Icinga/Web/Form/FormElement.php
/usr/share/php/Icinga/Web/Form/InvalidCSRFTokenException.php
/usr/share/php/Icinga/Web/Form/Validator/
/usr/share/php/Icinga/Web/Form/Validator/DateFormatValidator.php
/usr/share/php/Icinga/Web/Form/Validator/DateTimeValidator.php
/usr/share/php/Icinga/Web/Form/Validator/InArray.php
/usr/share/php/Icinga/Web/Form/Validator/ReadablePathValidator.php
/usr/share/php/Icinga/Web/Form/Validator/TimeFormatValidator.php
/usr/share/php/Icinga/Web/Form/Validator/TriStateValidator.php
/usr/share/php/Icinga/Web/Form/Validator/WritablePathValidator.php