/usr/share/php/Monolog/Handler/ is in php-monolog 1.23.0-1ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/php/Monolog/Handler/AbstractHandler.php
/usr/share/php/Monolog/Handler/AbstractProcessingHandler.php
/usr/share/php/Monolog/Handler/AbstractSyslogHandler.php
/usr/share/php/Monolog/Handler/AmqpHandler.php
/usr/share/php/Monolog/Handler/BrowserConsoleHandler.php
/usr/share/php/Monolog/Handler/BufferHandler.php
/usr/share/php/Monolog/Handler/ChromePHPHandler.php
/usr/share/php/Monolog/Handler/CouchDBHandler.php
/usr/share/php/Monolog/Handler/CubeHandler.php
/usr/share/php/Monolog/Handler/Curl/
/usr/share/php/Monolog/Handler/Curl/Util.php
/usr/share/php/Monolog/Handler/DeduplicationHandler.php
/usr/share/php/Monolog/Handler/DoctrineCouchDBHandler.php
/usr/share/php/Monolog/Handler/DynamoDbHandler.php
/usr/share/php/Monolog/Handler/ElasticSearchHandler.php
/usr/share/php/Monolog/Handler/ErrorLogHandler.php
/usr/share/php/Monolog/Handler/FilterHandler.php
/usr/share/php/Monolog/Handler/FingersCrossed/
/usr/share/php/Monolog/Handler/FingersCrossed/ActivationStrategyInterface.php
/usr/share/php/Monolog/Handler/FingersCrossed/ChannelLevelActivationStrategy.php
/usr/share/php/Monolog/Handler/FingersCrossed/ErrorLevelActivationStrategy.php
/usr/share/php/Monolog/Handler/FingersCrossedHandler.php
/usr/share/php/Monolog/Handler/FirePHPHandler.php
/usr/share/php/Monolog/Handler/FleepHookHandler.php
/usr/share/php/Monolog/Handler/FlowdockHandler.php
/usr/share/php/Monolog/Handler/GelfHandler.php
/usr/share/php/Monolog/Handler/GroupHandler.php
/usr/share/php/Monolog/Handler/HandlerInterface.php
/usr/share/php/Monolog/Handler/HandlerWrapper.php
/usr/share/php/Monolog/Handler/HipChatHandler.php
/usr/share/php/Monolog/Handler/IFTTTHandler.php
/usr/share/php/Monolog/Handler/LogEntriesHandler.php
/usr/share/php/Monolog/Handler/LogglyHandler.php
/usr/share/php/Monolog/Handler/MailHandler.php
/usr/share/php/Monolog/Handler/MandrillHandler.php
/usr/share/php/Monolog/Handler/MissingExtensionException.php
/usr/share/php/Monolog/Handler/MongoDBHandler.php
/usr/share/php/Monolog/Handler/NativeMailerHandler.php
/usr/share/php/Monolog/Handler/NewRelicHandler.php
/usr/share/php/Monolog/Handler/NullHandler.php
/usr/share/php/Monolog/Handler/PHPConsoleHandler.php
/usr/share/php/Monolog/Handler/PsrHandler.php
/usr/share/php/Monolog/Handler/PushoverHandler.php
/usr/share/php/Monolog/Handler/RavenHandler.php
/usr/share/php/Monolog/Handler/RedisHandler.php
/usr/share/php/Monolog/Handler/RollbarHandler.php
/usr/share/php/Monolog/Handler/RotatingFileHandler.php
/usr/share/php/Monolog/Handler/SamplingHandler.php
/usr/share/php/Monolog/Handler/Slack/
/usr/share/php/Monolog/Handler/Slack/SlackRecord.php
/usr/share/php/Monolog/Handler/SlackHandler.php
/usr/share/php/Monolog/Handler/SlackWebhookHandler.php
/usr/share/php/Monolog/Handler/SlackbotHandler.php
/usr/share/php/Monolog/Handler/SocketHandler.php
/usr/share/php/Monolog/Handler/StreamHandler.php
/usr/share/php/Monolog/Handler/SwiftMailerHandler.php
/usr/share/php/Monolog/Handler/SyslogHandler.php
/usr/share/php/Monolog/Handler/SyslogUdp/
/usr/share/php/Monolog/Handler/SyslogUdp/UdpSocket.php
/usr/share/php/Monolog/Handler/SyslogUdpHandler.php
/usr/share/php/Monolog/Handler/TestHandler.php
/usr/share/php/Monolog/Handler/WhatFailureGroupHandler.php
/usr/share/php/Monolog/Handler/ZendMonitorHandler.php