diff --git a/src/BusinessLogic/DataAccess/PromotionalWidgets/Entities/WidgetSettings.php b/src/BusinessLogic/DataAccess/PromotionalWidgets/Entities/WidgetSettings.php
index 980960d..2b91d02 100644
--- a/src/BusinessLogic/DataAccess/PromotionalWidgets/Entities/WidgetSettings.php
+++ b/src/BusinessLogic/DataAccess/PromotionalWidgets/Entities/WidgetSettings.php
@@ -31,7 +31,7 @@ class WidgetSettings extends Entity
     /**
      * @inheritDoc
      */
-    public function inflate(array $data): void
+    public function inflate(array $data)
     {
         parent::inflate($data);
 
diff --git a/src/BusinessLogic/Domain/OrderReport/OrderReporter.php b/src/BusinessLogic/Domain/OrderReport/OrderReporter.php
index 6dca39d..83c024d 100644
--- a/src/BusinessLogic/Domain/OrderReport/OrderReporter.php
+++ b/src/BusinessLogic/Domain/OrderReport/OrderReporter.php
@@ -53,7 +53,7 @@ public function toArray(): array
     /**
      * @inheritDoc
      */
-    public static function fromArray(array $array): Serializable
+    public static function fromArray(array $array)
     {
         $entity = parent::fromArray($array);
         $entity->page = intval($array['page']);
diff --git a/src/BusinessLogic/Domain/OrderReport/Tasks/OrderReportTask.php b/src/BusinessLogic/Domain/OrderReport/Tasks/OrderReportTask.php
index cc4db2c..537ba1a 100644
--- a/src/BusinessLogic/Domain/OrderReport/Tasks/OrderReportTask.php
+++ b/src/BusinessLogic/Domain/OrderReport/Tasks/OrderReportTask.php
@@ -64,7 +64,7 @@ public function __construct(string $merchantId, array $reportOrderIds, ?array $s
      *
      * @throws Exception
      */
-    public static function fromArray(array $array): Serializable
+    public static function fromArray(array $array)
     {
         return StoreContext::doWithStore($array['storeId'], static function () use ($array) {
             return new static($array['merchantId'], $array['reportOrderIds'], $array['statisticsOrderIds'] ?? null);
diff --git a/src/BusinessLogic/TransactionLog/Contracts/TransactionLogAwareInterface.php b/src/BusinessLogic/TransactionLog/Contracts/TransactionLogAwareInterface.php
index e9fa9d1..23e1452 100644
--- a/src/BusinessLogic/TransactionLog/Contracts/TransactionLogAwareInterface.php
+++ b/src/BusinessLogic/TransactionLog/Contracts/TransactionLogAwareInterface.php
@@ -23,8 +23,10 @@ public function getTransactionLog(): TransactionLog;
      * Sets transaction log.
      *
      * @param TransactionLog $transactionLog
+     *
+     * @return void
      */
-    public function setTransactionLog(TransactionLog $transactionLog): void;
+    public function setTransactionLog(TransactionLog $transactionLog);
 
     /**
      * Gets the store id for which the transactional task is created
diff --git a/src/BusinessLogic/Webhook/Tasks/OrderUpdateTask.php b/src/BusinessLogic/Webhook/Tasks/OrderUpdateTask.php
index f69b74c..0705f13 100644
--- a/src/BusinessLogic/Webhook/Tasks/OrderUpdateTask.php
+++ b/src/BusinessLogic/Webhook/Tasks/OrderUpdateTask.php
@@ -37,7 +37,7 @@ class OrderUpdateTask extends Task
      *
      * @throws Exception
      */
-    public static function fromArray(array $array): Serializable
+    public static function fromArray(array $array)
     {
         return StoreContext::doWithStore($array['storeId'], static function () use ($array) {
             return new static(
diff --git a/src/Infrastructure/AutoTest/AutoTestLogger.php b/src/Infrastructure/AutoTest/AutoTestLogger.php
index 712a4c9..7263d35 100644
--- a/src/Infrastructure/AutoTest/AutoTestLogger.php
+++ b/src/Infrastructure/AutoTest/AutoTestLogger.php
@@ -23,13 +23,9 @@ class AutoTestLogger extends Singleton implements ShopLoggerAdapter
     protected static $instance;
 
     /**
-     * Logs a message in system.
-     *
-     * @param LogData $data Data to log.
-     *
-     * @throws RepositoryNotRegisteredException
+     * @inheritDoc
      */
-    public function logMessage(LogData $data): void
+    public function logMessage(LogData $data)
     {
         $repo = RepositoryRegistry::getRepository(LogData::CLASS_NAME);
         $repo->save($data);
diff --git a/src/Infrastructure/AutoTest/AutoTestService.php b/src/Infrastructure/AutoTest/AutoTestService.php
index 703cb6f..bc39170 100644
--- a/src/Infrastructure/AutoTest/AutoTestService.php
+++ b/src/Infrastructure/AutoTest/AutoTestService.php
@@ -67,8 +67,10 @@ public function startAutoTest()
      * Activates the auto-test mode and registers the necessary components.
      *
      * @param bool $persist Indicates whether to store the mode change in configuration.
+     *
+     * @return void
      */
-    public function setAutoTestMode($persist = false): void
+    public function setAutoTestMode($persist = false)
     {
         Logger::resetInstance();
         ServiceRegister::registerService(
@@ -133,8 +135,10 @@ public function getAutoTestTaskStatus($queueItemId = 0)
      * re-initialize shop logger. Otherwise, logs and async calls will still use auto-test mode.
      *
      * @param callable $loggerInitializerDelegate Delegate that will give instance of the shop logger service.
+     *
+     * @return void
      */
-    public function stopAutoTestMode($loggerInitializerDelegate): void
+    public function stopAutoTestMode($loggerInitializerDelegate)
     {
         $this->getConfigService()->setAutoTestMode(false);
         ServiceRegister::registerService(ShopLoggerAdapter::CLASS_NAME, $loggerInitializerDelegate);
@@ -144,9 +148,11 @@ public function stopAutoTestMode($loggerInitializerDelegate): void
     /**
      * Deletes previous auto-test logs.
      *
+     * @return void
+     *
      * @throws RepositoryNotRegisteredException
      */
-    protected function deletePreviousLogs(): void
+    protected function deletePreviousLogs()
     {
         $repo = RepositoryRegistry::getRepository(LogData::getClassName());
         $logs = $repo->select();
@@ -157,8 +163,10 @@ protected function deletePreviousLogs(): void
 
     /**
      * Logs current HTTP configuration options.
+     *
+     * @return void
      */
-    protected function logHttpOptions(): void
+    protected function logHttpOptions()
     {
         $testDomain = parse_url($this->getConfigService()->getAsyncProcessUrl(''), PHP_URL_HOST);
         $options = array();
diff --git a/src/Infrastructure/AutoTest/AutoTestStatus.php b/src/Infrastructure/AutoTest/AutoTestStatus.php
index b3f66b0..9e2d4e6 100644
--- a/src/Infrastructure/AutoTest/AutoTestStatus.php
+++ b/src/Infrastructure/AutoTest/AutoTestStatus.php
@@ -58,7 +58,7 @@ public function __construct($taskStatus, $finished, $error, $logs)
      *
      * @return mixed[] This object as an array.
      */
-    public function toArray(): array
+    public function toArray()
     {
         return array(
             'taskStatus' => $this->taskStatus,
diff --git a/src/Infrastructure/AutoTest/AutoTestTask.php b/src/Infrastructure/AutoTest/AutoTestTask.php
index 67f311d..179f63a 100644
--- a/src/Infrastructure/AutoTest/AutoTestTask.php
+++ b/src/Infrastructure/AutoTest/AutoTestTask.php
@@ -4,7 +4,6 @@
 
 use SeQura\Core\Infrastructure\Logger\LogContextData;
 use SeQura\Core\Infrastructure\Logger\Logger;
-use SeQura\Core\Infrastructure\Serializer\Interfaces\Serializable;
 use SeQura\Core\Infrastructure\Serializer\Serializer;
 use SeQura\Core\Infrastructure\TaskExecution\Task;
 
@@ -39,7 +38,7 @@ public function __construct($data)
     /**
      * @inheritDoc
      */
-    public static function fromArray(array $array): Serializable
+    public static function fromArray(array $array)
     {
         return new static($array['data']);
     }
@@ -47,7 +46,7 @@ public static function fromArray(array $array): Serializable
     /**
      * @inheritDoc
      */
-    public function toArray(): array
+    public function toArray()
     {
         return array('data' => $this->data);
     }
@@ -63,17 +62,15 @@ public function __serialize()
     /**
      * @inheritDoc
      */
-    public function __unserialize($data): void
+    public function __unserialize($data)
     {
         $this->data = $data['data'];
     }
 
     /**
-     * String representation of object.
-     *
-     * @return string The string representation of the object or null.
+     * @inheritDoc
      */
-    public function serialize(): ?string
+    public function serialize()
     {
         return Serializer::serialize(array($this->data));
     }
@@ -91,9 +88,9 @@ public function unserialize($serialized)
     }
 
     /**
-     * Runs task logic.
+     * @inheritDoc
      */
-    public function execute(): void
+    public function execute()
     {
         $this->reportProgress(5);
         Logger::logInfo('Auto-test task started');
diff --git a/src/Infrastructure/BootstrapComponent.php b/src/Infrastructure/BootstrapComponent.php
index 14e30f1..010b5f8 100644
--- a/src/Infrastructure/BootstrapComponent.php
+++ b/src/Infrastructure/BootstrapComponent.php
@@ -29,8 +29,10 @@ class BootstrapComponent
 {
     /**
      * Initializes infrastructure components.
+     *
+     * @return void
      */
-    public static function init(): void
+    public static function init()
     {
         static::initServices();
         static::initRepositories();
@@ -39,8 +41,10 @@ public static function init(): void
 
     /**
      * Initializes services and utilities.
+     *
+     * @return void
      */
-    protected static function initServices(): void
+    protected static function initServices()
     {
         ServiceRegister::registerService(
             ConfigurationManager::CLASS_NAME,
@@ -118,15 +122,19 @@ function () {
 
     /**
      * Initializes repositories.
+     *
+     * @return void
      */
-    protected static function initRepositories(): void
+    protected static function initRepositories()
     {
     }
 
     /**
      * Initializes events.
+     *
+     * @return void
      */
-    protected static function initEvents(): void
+    protected static function initEvents()
     {
     }
 }
diff --git a/src/Infrastructure/Configuration/Configuration.php b/src/Infrastructure/Configuration/Configuration.php
index 15cd6a1..4077601 100644
--- a/src/Infrastructure/Configuration/Configuration.php
+++ b/src/Infrastructure/Configuration/Configuration.php
@@ -95,8 +95,10 @@ abstract public function getAsyncProcessUrl($guid);
      * Saves min log level in integration database.
      *
      * @param int $minLogLevel Min log level.
+     *
+     * @return void
      */
-    public function saveMinLogLevel($minLogLevel): void
+    public function saveMinLogLevel($minLogLevel)
     {
         $this->saveConfigValue('minLogLevel', $minLogLevel);
     }
@@ -115,8 +117,10 @@ public function getMinLogLevel()
      * Set default logger status (enabled/disabled).
      *
      * @param bool $status TRUE if default logger is enabled; otherwise, false.
+     *
+     * @return void
      */
-    public function setDefaultLoggerEnabled($status): void
+    public function setDefaultLoggerEnabled($status)
     {
         $this->saveConfigValue('defaultLoggerEnabled', $status);
     }
@@ -135,8 +139,10 @@ public function isDefaultLoggerEnabled()
      * Sets debug mode status (enabled/disabled).
      *
      * @param bool $status TRUE if debug mode is enabled; otherwise, false.
+     *
+     * @return void
      */
-    public function setDebugModeEnabled($status): void
+    public function setDebugModeEnabled($status)
     {
         $this->saveConfigValue('debugModeEnabled', (bool)$status);
     }
@@ -177,8 +183,10 @@ public function getMaxStartedTasksLimit()
      * can be in "in_progress" status at the same time.
      *
      * @param int $limit Max started tasks limit.
+     *
+     * @return void
      */
-    public function setMaxStartedTasksLimit($limit): void
+    public function setMaxStartedTasksLimit($limit)
     {
         $this->saveConfigValue('maxStartedTasksLimit', $limit);
     }
@@ -197,8 +205,10 @@ public function getAsyncStarterBatchSize()
      * Sets async process batch size.
      *
      * @param int $size
+     *
+     * @return void
      */
-    public function setAsyncStarterBatchSize($size): void
+    public function setAsyncStarterBatchSize($size)
     {
         $this->saveConfigValue('asyncStarterBatchSize', $size);
     }
@@ -218,8 +228,10 @@ public function getTaskRunnerWakeupDelay()
      * Sets task runner wakeup delay.
      *
      * @param int $delay Delay in seconds.
+     *
+     * @return void
      */
-    public function setTaskRunnerWakeupDelay($delay): void
+    public function setTaskRunnerWakeupDelay($delay)
     {
         $this->saveConfigValue('taskRunnerWakeupDelay', $delay);
     }
@@ -240,8 +252,10 @@ public function getTaskRunnerMaxAliveTime()
      * Sets max alive time.
      *
      * @param int $maxAliveTime Max alive time in seconds.
+     *
+     * @return void
      */
-    public function setTaskRunnerMaxAliveTime($maxAliveTime): void
+    public function setTaskRunnerMaxAliveTime($maxAliveTime)
     {
         $this->saveConfigValue('taskRunnerMaxAliveTime', $maxAliveTime);
     }
@@ -261,8 +275,10 @@ public function getMaxTaskExecutionRetries()
      * Sets max task execution retries.
      *
      * @param int $maxRetries Max number of retries.
+     *
+     * @return void
      */
-    public function setMaxTaskExecutionRetries($maxRetries): void
+    public function setMaxTaskExecutionRetries($maxRetries)
     {
         $this->saveConfigValue('maxTaskExecutionRetries', $maxRetries);
     }
@@ -282,8 +298,10 @@ public function getMaxTaskInactivityPeriod()
      * Sets max task inactivity period.
      *
      * @param int $maxInactivityPeriod Max inactivity period in seconds.
+     *
+     * @return void
      */
-    public function setMaxTaskInactivityPeriod($maxInactivityPeriod): void
+    public function setMaxTaskInactivityPeriod($maxInactivityPeriod)
     {
         $this->saveConfigValue('maxTaskInactivityPeriod', $maxInactivityPeriod);
     }
@@ -304,9 +322,11 @@ public function getTaskRunnerStatus()
      * @param string $guid Global unique identifier.
      * @param int|null $timestamp Timestamp.
      *
+     * @return void
+     *
      * @throws TaskRunnerStatusStorageUnavailableException
      */
-    public function setTaskRunnerStatus($guid, $timestamp): void
+    public function setTaskRunnerStatus($guid, $timestamp)
     {
         $taskRunnerStatus = array('guid' => $guid, 'timestamp' => $timestamp);
         $config = $this->saveConfigValue('taskRunnerStatus', $taskRunnerStatus);
@@ -340,8 +360,10 @@ public function getAutoConfigurationUrl()
      * Sets current auto-configuration state.
      *
      * @param string $state Current state.
+     *
+     * @return void
      */
-    public function setAutoConfigurationState($state): void
+    public function setAutoConfigurationState($state)
     {
         $this->saveConfigValue('autoConfigurationState', $state);
     }
@@ -368,8 +390,10 @@ public function getHttpConfigurationOptions($domain)
      *
      * @param string $domain A domain for which to save configuration options.
      * @param Options[] $options HTTP configuration options
+     *
+     * @return void
      */
-    public function setHttpConfigurationOptions($domain, array $options): void
+    public function setHttpConfigurationOptions($domain, array $options)
     {
         // get all current options and append new ones for given domain
         $data = json_decode($this->getConfigValue('httpConfigurationOptions', '[]'), true);
diff --git a/src/Infrastructure/Data/DataTransferObject.php b/src/Infrastructure/Data/DataTransferObject.php
index 7db3f13..038184a 100644
--- a/src/Infrastructure/Data/DataTransferObject.php
+++ b/src/Infrastructure/Data/DataTransferObject.php
@@ -69,7 +69,7 @@ public static function toBatchArray(array $batch)
      *
      * @return mixed[] Array representation of data transfer object.
      */
-    abstract public function toArray(): array;
+    abstract public function toArray();
 
     /**
      * Retrieves value from raw data.
diff --git a/src/Infrastructure/Logger/Interfaces/LoggerAdapter.php b/src/Infrastructure/Logger/Interfaces/LoggerAdapter.php
index b866013..7122444 100644
--- a/src/Infrastructure/Logger/Interfaces/LoggerAdapter.php
+++ b/src/Infrastructure/Logger/Interfaces/LoggerAdapter.php
@@ -15,6 +15,8 @@ interface LoggerAdapter
      * Log message in system
      *
      * @param LogData $data
+     *
+     * @return void
      */
-    public function logMessage(LogData $data): void;
+    public function logMessage(LogData $data);
 }
diff --git a/src/Infrastructure/Logger/LogContextData.php b/src/Infrastructure/Logger/LogContextData.php
index 8cf3b81..14b8498 100644
--- a/src/Infrastructure/Logger/LogContextData.php
+++ b/src/Infrastructure/Logger/LogContextData.php
@@ -67,7 +67,7 @@ public static function fromArray(array $data)
     /**
      * @inheritDoc
      */
-    public function toArray(): array
+    public function toArray()
     {
         return array(
             'name' => $this->getName(),
diff --git a/src/Infrastructure/Logger/LogData.php b/src/Infrastructure/Logger/LogData.php
index f8eb3d4..7cf41c1 100644
--- a/src/Infrastructure/Logger/LogData.php
+++ b/src/Infrastructure/Logger/LogData.php
@@ -101,7 +101,7 @@ public function __construct(
      *
      * @return EntityConfiguration Configuration object.
      */
-    public function getConfig(): EntityConfiguration
+    public function getConfig()
     {
         $map = new IndexMap();
         $map->addStringIndex('integration')
@@ -116,8 +116,10 @@ public function getConfig(): EntityConfiguration
      * Transforms raw array data to this entity instance.
      *
      * @param mixed[] $data Raw array data.
+     *
+     * @return void
      */
-    public function inflate(array $data): void
+    public function inflate(array $data)
     {
         parent::inflate($data);
 
diff --git a/src/Infrastructure/Logger/Logger.php b/src/Infrastructure/Logger/Logger.php
index 051f36a..446e9c8 100644
--- a/src/Infrastructure/Logger/Logger.php
+++ b/src/Infrastructure/Logger/Logger.php
@@ -67,8 +67,10 @@ protected function __construct()
      * @param string $message Message to log.
      * @param string $component Component for which to log message.
      * @param LogContextData[]|array $context Additional context data.
+     *
+     * @return void
      */
-    public static function logError($message, $component = 'Core', array $context = array()): void
+    public static function logError($message, $component = 'Core', array $context = array())
     {
         self::getInstance()->logMessage(self::ERROR, $message, $component, $context);
     }
@@ -79,8 +81,10 @@ public static function logError($message, $component = 'Core', array $context =
      * @param string $message Message to log.
      * @param string $component Component for which to log message.
      * @param LogContextData[]|array $context Additional context data.
+     *
+     * @return void
      */
-    public static function logWarning($message, $component = 'Core', array $context = array()): void
+    public static function logWarning($message, $component = 'Core', array $context = array())
     {
         self::getInstance()->logMessage(self::WARNING, $message, $component, $context);
     }
@@ -91,8 +95,10 @@ public static function logWarning($message, $component = 'Core', array $context
      * @param string $message Message to log.
      * @param string $component Component for which to log message.
      * @param LogContextData[]|array $context Additional context data.
+     *
+     * @return void
      */
-    public static function logInfo($message, $component = 'Core', array $context = array()): void
+    public static function logInfo($message, $component = 'Core', array $context = array())
     {
         self::getInstance()->logMessage(self::INFO, $message, $component, $context);
     }
@@ -103,8 +109,10 @@ public static function logInfo($message, $component = 'Core', array $context = a
      * @param string $message Message to log.
      * @param string $component Component for which to log message.
      * @param LogContextData[]|array $context Additional context data.
+     *
+     * @return void
      */
-    public static function logDebug($message, $component = 'Core', array $context = array()): void
+    public static function logDebug($message, $component = 'Core', array $context = array())
     {
         self::getInstance()->logMessage(self::DEBUG, $message, $component, $context);
     }
@@ -116,8 +124,10 @@ public static function logDebug($message, $component = 'Core', array $context =
      * @param string $message Message to log.
      * @param string $component Component for which to log message.
      * @param LogContextData[]|array $context Additional context data.
+     *
+     * @return void
      */
-    protected function logMessage($level, $message, $component, array $context = array()): void
+    protected function logMessage($level, $message, $component, array $context = array())
     {
         $config = LoggerConfiguration::getInstance();
         $logData = new LogData(
diff --git a/src/Infrastructure/Logger/LoggerConfiguration.php b/src/Infrastructure/Logger/LoggerConfiguration.php
index 36bf6f1..c85be54 100644
--- a/src/Infrastructure/Logger/LoggerConfiguration.php
+++ b/src/Infrastructure/Logger/LoggerConfiguration.php
@@ -57,8 +57,10 @@ class LoggerConfiguration extends Singleton
      * Set default logger status (turning on/off).
      *
      * @param bool $status
+     *
+     * @return void
      */
-    public static function setDefaultLoggerEnabled($status): void
+    public static function setDefaultLoggerEnabled($status)
     {
         self::getInstance()->setIsDefaultLoggerEnabled($status);
     }
@@ -68,8 +70,10 @@ public static function setDefaultLoggerEnabled($status): void
      *
      * @return bool
      *   Logger status true => enabled, false => disabled.
+     *
+     * @return bool
      */
-    public function isDefaultLoggerEnabled(): bool
+    public function isDefaultLoggerEnabled()
     {
         if (empty($this->isDefaultLoggerEnabled)) {
             try {
@@ -89,8 +93,10 @@ public function isDefaultLoggerEnabled(): bool
      * Set default logger status (enabled or disabled).
      *
      * @param bool $loggerStatus Logger status true => enabled, false => disabled.
+     *
+     * @return void
      */
-    public function setIsDefaultLoggerEnabled($loggerStatus): void
+    public function setIsDefaultLoggerEnabled($loggerStatus)
     {
         $this->getShopConfiguration()->setDefaultLoggerEnabled($loggerStatus);
         $this->isDefaultLoggerEnabled = $loggerStatus;
@@ -106,7 +112,7 @@ public function setIsDefaultLoggerEnabled($loggerStatus): void
      *    - info => 2
      *    - debug => 3
      */
-    public function getMinLogLevel(): int
+    public function getMinLogLevel()
     {
         if ($this->minLogLevel === null) {
             try {
@@ -125,8 +131,10 @@ public function getMinLogLevel(): int
      * Saves min log level in integration.
      *
      * @param int $minLogLevel Log level.
+     *
+     * @return void
      */
-    public function setMinLogLevel($minLogLevel): void
+    public function setMinLogLevel($minLogLevel)
     {
         $this->getShopConfiguration()->saveMinLogLevel($minLogLevel);
         $this->minLogLevel = $minLogLevel;
diff --git a/src/Infrastructure/ORM/Entity.php b/src/Infrastructure/ORM/Entity.php
index 0233388..dd708d1 100644
--- a/src/Infrastructure/ORM/Entity.php
+++ b/src/Infrastructure/ORM/Entity.php
@@ -42,7 +42,7 @@ public function __construct()
      *
      * @return string Fully qualified class name.
      */
-    public static function getClassName(): string
+    public static function getClassName()
     {
         return static::CLASS_NAME;
     }
@@ -54,7 +54,7 @@ public static function getClassName(): string
      *
      * @return static Transformed entity object.
      */
-    public static function fromArray(array $data): Entity
+    public static function fromArray(array $data)
     {
         $instance = new static();
         $instance->inflate($data);
@@ -67,14 +67,16 @@ public static function fromArray(array $data): Entity
      *
      * @return EntityConfiguration Configuration object.
      */
-    abstract public function getConfig(): EntityConfiguration;
+    abstract public function getConfig();
 
     /**
      * Sets raw array data to this entity instance properties.
      *
      * @param mixed[] $data Raw array data with keys for class fields. @see self::$fields for field names.
+     *
+     * @return void
      */
-    public function inflate(array $data): void
+    public function inflate(array $data)
     {
         foreach ($this->fields as $fieldName) {
             $this->$fieldName = static::getArrayValue($data, $fieldName, $this->$fieldName);
@@ -86,7 +88,7 @@ public function inflate(array $data): void
      *
      * @return mixed[] Entity in array format.
      */
-    public function toArray(): array
+    public function toArray()
     {
         $data = array('class_name' => static::getClassName());
         foreach ($this->fields as $fieldName) {
@@ -110,8 +112,10 @@ public function getId()
      * Sets entity identifier.
      *
      * @param int $id entity identifier.
+     *
+     * @return void
      */
-    public function setId($id): void
+    public function setId($id)
     {
         $this->id = $id;
     }
diff --git a/src/Infrastructure/ORM/Interfaces/ConditionallyDeletes.php b/src/Infrastructure/ORM/Interfaces/ConditionallyDeletes.php
index 2d106b5..79ebd95 100644
--- a/src/Infrastructure/ORM/Interfaces/ConditionallyDeletes.php
+++ b/src/Infrastructure/ORM/Interfaces/ConditionallyDeletes.php
@@ -11,5 +11,12 @@
  */
 interface ConditionallyDeletes
 {
-    public function deleteWhere(QueryFilter $queryFilter = null): void;
+    /**
+     * Deletes entities that match the given query filter.
+     *
+     * @param QueryFilter|null $queryFilter
+     *
+     * @return void
+     */
+    public function deleteWhere(QueryFilter $queryFilter = null);
 }
diff --git a/src/Infrastructure/ORM/Interfaces/MassInsert.php b/src/Infrastructure/ORM/Interfaces/MassInsert.php
index 8d7e4c6..f8f6912 100644
--- a/src/Infrastructure/ORM/Interfaces/MassInsert.php
+++ b/src/Infrastructure/ORM/Interfaces/MassInsert.php
@@ -10,6 +10,8 @@ interface MassInsert
      * Executes mass insert query for all provided entities
      *
      * @param Entity[] $entities
+     *
+     * @return void
      */
-    public function massInsert(array $entities): void;
+    public function massInsert(array $entities);
 }
diff --git a/src/Infrastructure/ORM/Interfaces/QueueItemRepository.php b/src/Infrastructure/ORM/Interfaces/QueueItemRepository.php
index e00df6b..4d81a9b 100644
--- a/src/Infrastructure/ORM/Interfaces/QueueItemRepository.php
+++ b/src/Infrastructure/ORM/Interfaces/QueueItemRepository.php
@@ -42,7 +42,7 @@ public function findOldestQueuedItems($priority, $limit = 10);
      * @return int Id of saved queue item
      * @throws QueueItemSaveException if queue item could not be saved
      */
-    public function saveWithCondition(QueueItem $queueItem, array $additionalWhere = array()): int;
+    public function saveWithCondition(QueueItem $queueItem, array $additionalWhere = array());
 
     /**
      * Updates status of a batch of queue items.
@@ -52,5 +52,5 @@ public function saveWithCondition(QueueItem $queueItem, array $additionalWhere =
      *
      * @return void
      */
-    public function batchStatusUpdate(array $ids, $status): void;
+    public function batchStatusUpdate(array $ids, $status);
 }
diff --git a/src/Infrastructure/ORM/Interfaces/RepositoryInterface.php b/src/Infrastructure/ORM/Interfaces/RepositoryInterface.php
index 44d2a41..4cb2ea6 100644
--- a/src/Infrastructure/ORM/Interfaces/RepositoryInterface.php
+++ b/src/Infrastructure/ORM/Interfaces/RepositoryInterface.php
@@ -28,8 +28,10 @@ public static function getClassName();
      * Sets repository entity.
      *
      * @param string $entityClass Repository entity class.
+     *
+     * @return void
      */
-    public function setEntityClass(string $entityClass): void;
+    public function setEntityClass($entityClass);
 
     /**
      * Executes select query.
diff --git a/src/Infrastructure/ORM/IntermediateObject.php b/src/Infrastructure/ORM/IntermediateObject.php
index 225e298..e2be66c 100644
--- a/src/Infrastructure/ORM/IntermediateObject.php
+++ b/src/Infrastructure/ORM/IntermediateObject.php
@@ -45,15 +45,17 @@ class IntermediateObject
     /**
      * @return string|null
      */
-    public function getIndex1(): ?string
+    public function getIndex1()
     {
         return $this->index1;
     }
 
     /**
      * @param string $index1
+     *
+     * @return void
      */
-    public function setIndex1(string $index1): void
+    public function setIndex1($index1)
     {
         $this->index1 = $index1;
     }
@@ -61,15 +63,17 @@ public function setIndex1(string $index1): void
     /**
      * @return string|null
      */
-    public function getIndex2(): ?string
+    public function getIndex2()
     {
         return $this->index2;
     }
 
     /**
      * @param string $index2
+     *
+     * @return void
      */
-    public function setIndex2(string $index2): void
+    public function setIndex2($index2)
     {
         $this->index2 = $index2;
     }
@@ -84,8 +88,10 @@ public function getIndex3(): ?string
 
     /**
      * @param string $index3
+     *
+     * @return void
      */
-    public function setIndex3(string $index3): void
+    public function setIndex3($index3)
     {
         $this->index3 = $index3;
     }
@@ -93,15 +99,17 @@ public function setIndex3(string $index3): void
     /**
      * @return string|null
      */
-    public function getIndex4(): ?string
+    public function getIndex4()
     {
         return $this->index4;
     }
 
     /**
      * @param string $index4
+     *
+     * @return void
      */
-    public function setIndex4(string $index4): void
+    public function setIndex4($index4)
     {
         $this->index4 = $index4;
     }
@@ -109,15 +117,17 @@ public function setIndex4(string $index4): void
     /**
      * @return string|null
      */
-    public function getIndex5(): ?string
+    public function getIndex5()
     {
         return $this->index5;
     }
 
     /**
      * @param string $index5
+     *
+     * @return void
      */
-    public function setIndex5(string $index5): void
+    public function setIndex5($index5)
     {
         $this->index5 = $index5;
     }
@@ -125,15 +135,17 @@ public function setIndex5(string $index5): void
     /**
      * @return string|null
      */
-    public function getIndex6(): ?string
+    public function getIndex6()
     {
         return $this->index6;
     }
 
     /**
      * @param string $index6
+     *
+     * @return void
      */
-    public function setIndex6(string $index6): void
+    public function setIndex6($index6)
     {
         $this->index6 = $index6;
     }
@@ -141,15 +153,17 @@ public function setIndex6(string $index6): void
     /**
      * @return string|null
      */
-    public function getData(): ?string
+    public function getData()
     {
         return $this->data;
     }
 
     /**
      * @param string $data
+     *
+     * @return void
      */
-    public function setData(string $data): void
+    public function setData($data)
     {
         $this->data = $data;
     }
@@ -159,8 +173,10 @@ public function setData(string $data): void
      *
      * @param mixed $index
      * @param mixed $value
+     *
+     * @return void
      */
-    public function setIndexValue($index, $value): void
+    public function setIndexValue($index, $value)
     {
         if (!is_int($index) || $index < 1 || !is_string($value)) {
             return;
@@ -181,7 +197,7 @@ public function setIndexValue($index, $value): void
      *
      * @return string|null
      */
-    public function getIndexValue($index): ?string
+    public function getIndexValue($index)
     {
         $value = null;
         if (!is_int($index) || $index < 1) {
diff --git a/src/Infrastructure/ORM/QueryFilter/QueryFilter.php b/src/Infrastructure/ORM/QueryFilter/QueryFilter.php
index b8ce201..2365911 100644
--- a/src/Infrastructure/ORM/QueryFilter/QueryFilter.php
+++ b/src/Infrastructure/ORM/QueryFilter/QueryFilter.php
@@ -52,7 +52,7 @@ class QueryFilter
      *
      * @return int|null Limit for select.
      */
-    public function getLimit(): ?int
+    public function getLimit()
     {
         return $this->limit;
     }
@@ -64,7 +64,7 @@ public function getLimit(): ?int
      *
      * @return self This instance for chaining.
      */
-    public function setLimit(int $limit): QueryFilter
+    public function setLimit($limit)
     {
         $this->limit = $limit;
 
@@ -76,7 +76,7 @@ public function setLimit(int $limit): QueryFilter
      *
      * @return int|null Offset.
      */
-    public function getOffset(): ?int
+    public function getOffset()
     {
         return $this->offset;
     }
@@ -88,7 +88,7 @@ public function getOffset(): ?int
      *
      * @return self This instance for chaining.
      */
-    public function setOffset(int $offset): QueryFilter
+    public function setOffset($offset)
     {
         $this->offset = $offset;
 
@@ -105,7 +105,7 @@ public function setOffset(int $offset): QueryFilter
      *
      * @throws QueryFilterInvalidParamException
      */
-    public function orderBy($column, string $direction = self::ORDER_ASC): QueryFilter
+    public function orderBy($column, $direction = self::ORDER_ASC)
     {
         if (!is_string($column) || !in_array($direction, array(self::ORDER_ASC, self::ORDER_DESC), false)) {
             throw new QueryFilterInvalidParamException(
@@ -124,7 +124,7 @@ public function orderBy($column, string $direction = self::ORDER_ASC): QueryFilt
      *
      * @return string|null Order column name.
      */
-    public function getOrderByColumn(): ?string
+    public function getOrderByColumn()
     {
         return $this->orderByColumn;
     }
@@ -134,7 +134,7 @@ public function getOrderByColumn(): ?string
      *
      * @return string|null Order direction (@see self::ORDER_ASC or @see self::ORDER_DESC)
      */
-    public function getOrderDirection(): ?string
+    public function getOrderDirection()
     {
         return $this->orderDirection;
     }
@@ -144,7 +144,7 @@ public function getOrderDirection(): ?string
      *
      * @return QueryCondition[] Filter conditions.
      */
-    public function getConditions(): array
+    public function getConditions()
     {
         return $this->conditions;
     }
@@ -160,7 +160,7 @@ public function getConditions(): array
      *
      * @throws QueryFilterInvalidParamException
      */
-    public function where(string $column, string $operator, $value = null): QueryFilter
+    public function where($column, $operator, $value = null)
     {
         $this->validateConditionParameters($column, $operator, $value);
 
@@ -180,7 +180,7 @@ public function where(string $column, string $operator, $value = null): QueryFil
      *
      * @throws QueryFilterInvalidParamException
      */
-    public function orWhere(string $column, string $operator, $value = null): QueryFilter
+    public function orWhere($column, $operator, $value = null)
     {
         $this->validateConditionParameters($column, $operator, $value);
 
@@ -196,9 +196,11 @@ public function orWhere(string $column, string $operator, $value = null): QueryF
      * @param mixed $operator Operator. Use constants from @see Operator class.
      * @param mixed $value Value of condition.
      *
+     * @return void
+     *
      * @throws QueryFilterInvalidParamException
      */
-    protected function validateConditionParameters($column, $operator, $value): void
+    protected function validateConditionParameters($column, $operator, $value)
     {
         if (!is_string($column) || !is_string($operator)) {
             throw new QueryFilterInvalidParamException('Column and operator values must be string types');
diff --git a/src/Infrastructure/ORM/RepositoryRegistry.php b/src/Infrastructure/ORM/RepositoryRegistry.php
index 234bca9..17d32e1 100644
--- a/src/Infrastructure/ORM/RepositoryRegistry.php
+++ b/src/Infrastructure/ORM/RepositoryRegistry.php
@@ -33,7 +33,7 @@ class RepositoryRegistry
      *
      * @throws RepositoryNotRegisteredException
      */
-    public static function getRepository(string $entityClass): RepositoryInterface
+    public static function getRepository($entityClass)
     {
         if (!static::isRegistered($entityClass)) {
             throw new RepositoryNotRegisteredException("Repository for entity $entityClass not found or registered.");
@@ -58,9 +58,11 @@ public static function getRepository(string $entityClass): RepositoryInterface
      * @param string $entityClass Class name of entity.
      * @param string $repositoryClass Class name of repository.
      *
+     * @return void
+     *
      * @throws RepositoryClassException
      */
-    public static function registerRepository(string $entityClass, string $repositoryClass): void
+    public static function registerRepository($entityClass, $repositoryClass)
     {
         if (!is_subclass_of($repositoryClass, RepositoryInterface::CLASS_NAME)) {
             throw new RepositoryClassException("Class $repositoryClass is not implementation of RepositoryInterface.");
@@ -77,7 +79,7 @@ public static function registerRepository(string $entityClass, string $repositor
      *
      * @return boolean Returns TRUE if repository has been registered; FALSE otherwise.
      */
-    public static function isRegistered(string $entityClass): bool
+    public static function isRegistered($entityClass)
     {
         return isset(static::$repositories[$entityClass]);
     }
@@ -90,7 +92,7 @@ public static function isRegistered(string $entityClass): bool
      * @throws RepositoryClassException
      * @throws RepositoryNotRegisteredException
      */
-    public static function getQueueItemRepository(): QueueItemRepository
+    public static function getQueueItemRepository()
     {
         /**
          * @var QueueItemRepository $repository
diff --git a/src/Infrastructure/ORM/Utility/EntityTranslator.php b/src/Infrastructure/ORM/Utility/EntityTranslator.php
index a5ba254..087afdb 100644
--- a/src/Infrastructure/ORM/Utility/EntityTranslator.php
+++ b/src/Infrastructure/ORM/Utility/EntityTranslator.php
@@ -21,9 +21,11 @@ class EntityTranslator
     /**
      * @param string $entityClass
      *
+     * @return void
+     *
      * @throws EntityClassException
      */
-    public function init(string $entityClass): void
+    public function init($entityClass)
     {
         if (!is_subclass_of($entityClass, Entity::getClassName())) {
             throw new EntityClassException("Class $entityClass is not implementation of Entity");
diff --git a/src/Infrastructure/ORM/Utility/IndexHelper.php b/src/Infrastructure/ORM/Utility/IndexHelper.php
index e977820..13e14e6 100644
--- a/src/Infrastructure/ORM/Utility/IndexHelper.php
+++ b/src/Infrastructure/ORM/Utility/IndexHelper.php
@@ -19,7 +19,7 @@ class IndexHelper
      *
      * @return array<string,int> Map of property indexes
      */
-    public static function mapFieldsToIndexes(Entity $entity): array
+    public static function mapFieldsToIndexes(Entity $entity)
     {
         $result = array();
         $config = $entity->getConfig();
@@ -38,7 +38,7 @@ public static function mapFieldsToIndexes(Entity $entity): array
      *
      * @return string[]
      */
-    public static function transformFieldsToIndexes(Entity $entity): array
+    public static function transformFieldsToIndexes(Entity $entity)
     {
         $result = array();
         $config = $entity->getConfig();
@@ -59,7 +59,7 @@ public static function transformFieldsToIndexes(Entity $entity): array
      *
      * @return mixed[]|string|null
      */
-    public static function castFieldValue($value, string $type)
+    public static function castFieldValue($value, $type)
     {
         if ($value === null || is_string($value)) {
             return $value;
diff --git a/src/Infrastructure/Serializer/Interfaces/Serializable.php b/src/Infrastructure/Serializer/Interfaces/Serializable.php
index 49410a9..90d0897 100644
--- a/src/Infrastructure/Serializer/Interfaces/Serializable.php
+++ b/src/Infrastructure/Serializer/Interfaces/Serializable.php
@@ -17,14 +17,14 @@ interface Serializable extends \Serializable
      * @return static
      *      Instance of serialized object.
      */
-    public static function fromArray(array $array): Serializable;
+    public static function fromArray(array $array);
 
     /**
      * Transforms serializable object into an array.
      *
      * @return array<mixed> Array representation of a serializable object.
      */
-    public function toArray(): array;
+    public function toArray();
 
     /**
      * @return array<mixed>
@@ -36,5 +36,5 @@ public function __serialize();
      *
      * @return void
      */
-    public function __unserialize(array $data): void;
+    public function __unserialize(array $data);
 }
diff --git a/src/Infrastructure/ServiceRegister.php b/src/Infrastructure/ServiceRegister.php
index 81f956d..bf5d6d3 100644
--- a/src/Infrastructure/ServiceRegister.php
+++ b/src/Infrastructure/ServiceRegister.php
@@ -49,7 +49,7 @@ protected function __construct(array $services = array())
      *
      * @return ServiceRegister
      */
-    public static function getInstance(): ServiceRegister
+    public static function getInstance()
     {
         if (self::$instance === null) {
             self::$instance = new ServiceRegister();
@@ -67,7 +67,7 @@ public static function getInstance(): ServiceRegister
      *
      * @return T
      */
-    public static function getService(string $type)
+    public static function getService($type)
     {
         return self::getInstance()->get($type);
     }
@@ -78,10 +78,12 @@ public static function getService(string $type)
      * @param string $type Type of service. Should be fully qualified class name.
      * @param callable $delegate Delegate that will give instance of registered service.
      *
+     * @return void
+     *
      * @throws InvalidArgumentException
      *  In case delegate is not a callable.
      */
-    public static function registerService(string $type, callable $delegate): void
+    public static function registerService($type, $delegate)
     {
         self::getInstance()->register($type, $delegate);
     }
@@ -92,10 +94,12 @@ public static function registerService(string $type, callable $delegate): void
      * @param string $type Type of service. Should be fully qualified class name.
      * @param callable $delegate Delegate that will give instance of registered service.
      *
+     * @return void
+     *
      * @throws InvalidArgumentException
      *  In case delegate is not a callable.
      */
-    protected function register(string $type, callable $delegate): void
+    protected function register(string $type, callable $delegate)
     {
         if (!is_callable($delegate)) {
             throw new InvalidArgumentException("$type delegate is not callable.");
diff --git a/src/Infrastructure/Singleton.php b/src/Infrastructure/Singleton.php
index dee2702..ad79863 100644
--- a/src/Infrastructure/Singleton.php
+++ b/src/Infrastructure/Singleton.php
@@ -47,8 +47,10 @@ public static function getInstance()
 
     /**
      * Resets singleton instance. Required for proper tests.
+     *
+     * @return void
      */
-    public static function resetInstance(): void
+    public static function resetInstance()
     {
         static::$instance = null;
     }
diff --git a/src/Infrastructure/TaskExecution/AsyncBatchStarter.php b/src/Infrastructure/TaskExecution/AsyncBatchStarter.php
index 5375c6a..8115cde 100644
--- a/src/Infrastructure/TaskExecution/AsyncBatchStarter.php
+++ b/src/Infrastructure/TaskExecution/AsyncBatchStarter.php
@@ -48,7 +48,7 @@ class AsyncBatchStarter implements Runnable
     /**
      * @inheritDoc
      */
-    public function serialize(): ?string
+    public function serialize()
     {
         return Serializer::serialize(array($this->batchSize, $this->subBatches, $this->runners, $this->addIndex));
     }
@@ -67,7 +67,7 @@ public function unserialize($data)
     /**
      * @inheritDoc
      */
-    public static function fromArray(array $array): Serializable
+    public static function fromArray(array $array)
     {
         $runners = array();
         $subBatches = array();
@@ -89,7 +89,7 @@ public static function fromArray(array $array): Serializable
     /**
      * @inheritDoc
      */
-    public function toArray(): array
+    public function toArray()
     {
         $runners = array();
         $subBatches = array();
@@ -120,7 +120,7 @@ public function __serialize()
     /**
      * @inheritDoc
      */
-    public function __unserialize($data): void
+    public function __unserialize($data)
     {
         $this->batchSize = $data['batchSize'];
         $this->addIndex = $data['addIndex'];
@@ -146,7 +146,7 @@ public function __unserialize($data): void
      * @param int $batchSize
      * @param Runnable[] $runners
      */
-    public function __construct(int $batchSize, array $runners = array())
+    public function __construct($batchSize, array $runners = array())
     {
         $this->batchSize = $batchSize;
         foreach ($runners as $runner) {
@@ -158,8 +158,10 @@ public function __construct(int $batchSize, array $runners = array())
      * Add runnable to the batch
      *
      * @param Runnable $runner
+     *
+     * @return void
      */
-    public function addRunner(Runnable $runner): void
+    public function addRunner(Runnable $runner)
     {
         if ($this->isCapacityFull()) {
             $this->subBatches[$this->addIndex]->addRunner($runner);
@@ -181,7 +183,7 @@ public function addRunner(Runnable $runner): void
      *
      * @throws ProcessStarterSaveException
      */
-    public function run(): void
+    public function run()
     {
         foreach ($this->subBatches as $subBatch) {
             $this->getAsyncProcessStarter()->start($subBatch);
@@ -198,7 +200,7 @@ public function run(): void
      *
      * @return int Max number of nested sub-batch levels
      */
-    public function getMaxNestingLevels(): int
+    public function getMaxNestingLevels()
     {
         if (empty($this->subBatches)) {
             return 0;
@@ -223,17 +225,17 @@ public function getMaxNestingLevels(): int
      *
      * @return float Wait period in micro seconds that is required for whole batch (with sub-batches) to run
      */
-    public function getWaitTime(float $requestDuration)
+    public function getWaitTime($requestDuration)
     {
         // Without sub-batches all requests are started as soon as run method is done
         if (empty($this->subBatches)) {
-            return 0;
+            return 0.0;
         }
 
         $subBatchWaitTime = $this->batchSize * $this->getMaxNestingLevels() * $requestDuration;
         $runnersStartupTime = count($this->runners) * $requestDuration;
 
-        return $subBatchWaitTime - $runnersStartupTime;
+        return (float) $subBatchWaitTime - $runnersStartupTime;
     }
 
     /**
@@ -254,7 +256,7 @@ public function __toString()
      * @return bool
      *      True if current batch cant take any more runners nor create any more sub-batches itself; False otherwise
      */
-    protected function isCapacityFull(): bool
+    protected function isCapacityFull()
     {
         return $this->isRunnersCapacityFull() && $this->isSubBatchCapacityFull();
     }
@@ -263,7 +265,7 @@ protected function isCapacityFull(): bool
      * @return bool
      *      True if current batch cant create any more sub-batches itself; False otherwise
      */
-    protected function isSubBatchCapacityFull(): bool
+    protected function isSubBatchCapacityFull()
     {
         return count($this->subBatches) >= $this->batchSize;
     }
@@ -283,7 +285,7 @@ protected function isRunnersCapacityFull(): bool
      * @return AsyncProcessService
      *   Instance of async process starter.
      */
-    protected function getAsyncProcessStarter(): AsyncProcessService
+    protected function getAsyncProcessStarter()
     {
         if ($this->asyncProcessStarter === null) {
             $this->asyncProcessStarter = ServiceRegister::getService(AsyncProcessService::CLASS_NAME);
diff --git a/src/Infrastructure/TaskExecution/AsyncProcessStarterService.php b/src/Infrastructure/TaskExecution/AsyncProcessStarterService.php
index 67b9dbd..b29348b 100644
--- a/src/Infrastructure/TaskExecution/AsyncProcessStarterService.php
+++ b/src/Infrastructure/TaskExecution/AsyncProcessStarterService.php
@@ -77,10 +77,12 @@ protected function __construct()
      *
      * @param Runnable $runner Runner that should be started async.
      *
+     * @return void
+     *
      * @throws HttpRequestException
      * @throws ProcessStarterSaveException
      */
-    public function start(Runnable $runner): void
+    public function start(Runnable $runner)
     {
         $guid = trim($this->guidProvider->generateGuid());
 
@@ -92,8 +94,10 @@ public function start(Runnable $runner): void
      * Runs a process with provided identifier.
      *
      * @param string $guid Identifier of process.
+     *
+     * @return void
      */
-    public function runProcess($guid): void
+    public function runProcess($guid)
     {
         try {
             $filter = new QueryFilter();
@@ -125,9 +129,11 @@ public function runProcess($guid): void
      * @param string $guid Unique process identifier.
      * @param Runnable $runner Runner instance.
      *
+     * @return void
+     *
      * @throws ProcessStarterSaveException
      */
-    protected function saveGuidAndRunner(string $guid, Runnable $runner): void
+    protected function saveGuidAndRunner($guid, Runnable $runner)
     {
         try {
             $process = new Process();
@@ -146,9 +152,11 @@ protected function saveGuidAndRunner(string $guid, Runnable $runner): void
      *
      * @param string $guid Unique process identifier.
      *
+     * @return void
+     *
      * @throws HttpRequestException
      */
-    protected function startRunnerAsynchronously(string $guid): void
+    protected function startRunnerAsynchronously($guid)
     {
         try {
             $this->httpClient->requestAsync(
diff --git a/src/Infrastructure/TaskExecution/Composite/ExecutionDetails.php b/src/Infrastructure/TaskExecution/Composite/ExecutionDetails.php
index 3407eb5..9e3b676 100644
--- a/src/Infrastructure/TaskExecution/Composite/ExecutionDetails.php
+++ b/src/Infrastructure/TaskExecution/Composite/ExecutionDetails.php
@@ -75,8 +75,10 @@ public function getProgress()
 
     /**
      * @param float $progress
+     *
+     * @return void
      */
-    public function setProgress(float $progress): void
+    public function setProgress($progress)
     {
         $this->progress = $progress;
     }
@@ -100,7 +102,7 @@ public function unserialize($data)
     /**
      * @inheritDoc
      */
-    public function toArray(): array
+    public function toArray()
     {
         return [
             'progress' => $this->getProgress(),
@@ -120,7 +122,7 @@ public function __serialize()
     /**
      * @inheritDoc
      */
-    public function __unserialize($data): void
+    public function __unserialize($data)
     {
         $this->progress = $data['progress'];
         $this->executionId = $data['executionId'];
@@ -130,7 +132,7 @@ public function __unserialize($data): void
     /**
      * @return ExecutionDetails
      */
-    public static function fromArray(array $array): Serializable
+    public static function fromArray(array $array)
     {
         $entity = new static($array['executionId'], $array['weight']);
         $entity->setProgress($array['progress']);
diff --git a/src/Infrastructure/TaskExecution/Composite/Orchestrator.php b/src/Infrastructure/TaskExecution/Composite/Orchestrator.php
index 73b9015..29fe0d2 100644
--- a/src/Infrastructure/TaskExecution/Composite/Orchestrator.php
+++ b/src/Infrastructure/TaskExecution/Composite/Orchestrator.php
@@ -39,7 +39,7 @@ public function __construct()
     /**
      * @inheritDoc
      */
-    public function serialize(): ?string
+    public function serialize()
     {
         $taskList = [];
         foreach ($this->taskList as $data) {
@@ -63,7 +63,7 @@ public function unserialize($serialized)
     /**
      * @inheritDoc
      */
-    public static function fromArray(array $array): \SeQura\Core\Infrastructure\Serializer\Interfaces\Serializable
+    public static function fromArray(array $array)
     {
         $entity = new static();
         foreach ($array['taskList'] as $data) {
@@ -97,7 +97,7 @@ public function __serialize()
     /**
      * @inheritDoc
      */
-    public function __unserialize($data): void
+    public function __unserialize($data)
     {
         $taskList = array();
         foreach ($data['taskList'] as $task) {
@@ -110,9 +110,11 @@ public function __unserialize($data): void
     /**
      * Creates subtasks.
      *
+     * @return void
+     *
      * @final
      */
-    public function execute(): void
+    public function execute()
     {
         while ($task = $this->getSubTask()) {
             $this->taskList[] = $task;
@@ -136,16 +138,18 @@ public function execute(): void
      * @param int $executionId Sub-Job id.
      * @param int|float $progress Between 0 and 100, inclusive.
      *
+     * @return void
+     *
      * @final
      */
-    public function updateSubJobProgress(int $executionId, $progress): void
+    public function updateSubJobProgress($executionId, $progress)
     {
         if ($progress > 100 || $progress < 0) {
-            throw new InvalidArgumentException("Invalid progress ${progress} provided. ");
+            throw new InvalidArgumentException("Invalid progress $progress provided. ");
         }
 
         if (!($subJob = $this->getSubJob($executionId))) {
-            throw new InvalidArgumentException("Provided execution with id ${executionId} not found in task list");
+            throw new InvalidArgumentException("Provided execution with id $executionId not found in task list");
         }
 
         $subJob->setProgress($progress);
@@ -154,18 +158,20 @@ public function updateSubJobProgress(int $executionId, $progress): void
 
     /**
      * @inheritDoc
+     *
      * @final
      */
-    public function onFail(): void
+    public function onFail()
     {
         $this->abortSubJobs();
     }
 
     /**
      * @inheritDoc
+     *
      * @final
      */
-    public function onAbort(): void
+    public function onAbort()
     {
         $this->abortSubJobs();
     }
@@ -175,7 +181,7 @@ public function onAbort(): void
      *
      * @return ExecutionDetails | null
      */
-    abstract protected function getSubTask(): ?ExecutionDetails;
+    abstract protected function getSubTask();
 
     /**
      * Creates sub-job.
@@ -187,7 +193,7 @@ abstract protected function getSubTask(): ?ExecutionDetails;
      *
      * @throws QueueStorageUnavailableException
      */
-    protected function createSubJob(Task $task, int $weight = 1): ExecutionDetails
+    protected function createSubJob(Task $task, $weight = 1)
     {
         $queueItem = $this->getQueueService()->create($this->getSubJobQueueName(), $task, $this->getContext(), Priority::NORMAL, $this->getExecutionId());
 
@@ -217,7 +223,7 @@ protected function calculateProgress()
      *
      * @return string
      */
-    protected function getSubJobQueueName(): string
+    protected function getSubJobQueueName()
     {
         return static::QUEUE_NAME_PREFIX . $this->getExecutionId();
     }
@@ -227,7 +233,7 @@ protected function getSubJobQueueName(): string
      *
      * @return QueueService
      */
-    protected function getQueueService(): QueueService
+    protected function getQueueService()
     {
         return ServiceRegister::getService(QueueService::CLASS_NAME);
     }
@@ -254,7 +260,7 @@ protected function getContext(): string
      *
      * @return ExecutionDetails | false
      */
-    protected function getSubJob(int $executionId)
+    protected function getSubJob($executionId)
     {
         return current(array_filter(
             $this->taskList,
@@ -266,8 +272,10 @@ static function (ExecutionDetails $d) use ($executionId) {
 
     /**
      * Aborts incomplete sub-jobs.
+     *
+     * @return void
      */
-    protected function abortSubJobs(): void
+    protected function abortSubJobs()
     {
         $ids = [];
         foreach ($this->taskList as $task) {
@@ -285,8 +293,10 @@ protected function abortSubJobs(): void
 
     /**
      * Starts sub-jobs.
+     *
+     * @return void
      */
-    protected function startSubJobs(): void
+    protected function startSubJobs()
     {
         $ids = array_map(static function (ExecutionDetails $d) {
             return $d->getExecutionId();
diff --git a/src/Infrastructure/TaskExecution/CompositeTask.php b/src/Infrastructure/TaskExecution/CompositeTask.php
index 6f2348e..69b04e7 100644
--- a/src/Infrastructure/TaskExecution/CompositeTask.php
+++ b/src/Infrastructure/TaskExecution/CompositeTask.php
@@ -51,7 +51,7 @@ abstract class CompositeTask extends Task
      * @param mixed[] $subTasks List of all tasks for this composite task. Key is task FQN and value is percentage share.
      * @param int $initialProgress Initial progress in percents.
      */
-    public function __construct(array $subTasks, int $initialProgress = 0)
+    public function __construct(array $subTasks, $initialProgress = 0)
     {
         parent::__construct();
         $this->initialProgress = $initialProgress;
@@ -76,7 +76,7 @@ public function __construct(array $subTasks, int $initialProgress = 0)
      * @return Serializable
      *      Instance of serialized object.
      */
-    public static function fromArray(array $array): Serializable
+    public static function fromArray(array $array)
     {
         $tasks = array();
 
@@ -103,7 +103,7 @@ public static function fromArray(array $array): Serializable
      *
      * @return static
      */
-    protected static function createTask(array $tasks, int $initialProgress): CompositeTask
+    protected static function createTask(array $tasks, int $initialProgress)
     {
         return new static($tasks, $initialProgress);
     }
@@ -113,7 +113,7 @@ protected static function createTask(array $tasks, int $initialProgress): Compos
      *
      * @return mixed[] Array representation of a serializable object.
      */
-    public function toArray(): array
+    public function toArray()
     {
         $tasks = array();
 
@@ -140,7 +140,7 @@ public function __serialize()
     /**
      * @inheritDoc
      */
-    public function __unserialize($data): void
+    public function __unserialize($data)
     {
         $this->initialProgress = $data['initial_progress'];
         $this->taskProgressMap = $data['task_progress_map'];
@@ -159,7 +159,7 @@ public function __unserialize($data): void
     /**
      * @inheritdoc
      */
-    public function serialize(): ?string
+    public function serialize()
     {
         return Serializer::serialize(
             array(
@@ -189,8 +189,10 @@ public function unserialize($serialized)
     /**
      * Called upon composite task deserialization.
      * Allows bootstrapping operations to be completed when the deserialization is complete.
+     *
+     * @return void
      */
-    public function onUnserialized(): void
+    public function onUnserialized()
     {
         $this->registerSubTasksEvents();
     }
@@ -200,9 +202,11 @@ public function onUnserialized(): void
      *
      * @final
      *
+     * @return void
+     *
      * @throws AbortTaskExecutionException
      */
-    public function execute(): void
+    public function execute()
     {
         while ($activeTask = $this->getActiveTask()) {
             $this->executeSubTask($activeTask);
@@ -214,7 +218,7 @@ public function execute(): void
      *
      * @return bool TRUE if active task can be reconfigures; otherwise, FALSE.
      */
-    public function canBeReconfigured(): bool
+    public function canBeReconfigured()
     {
         $activeTask = $this->getActiveTask();
 
@@ -222,9 +226,9 @@ public function canBeReconfigured(): bool
     }
 
     /**
-     * Reconfigures the task.
+     * @inheritdoc
      */
-    public function reconfigure(): void
+    public function reconfigure()
     {
         $activeTask = $this->getActiveTask();
 
@@ -238,7 +242,7 @@ public function reconfigure(): void
      *
      * @return mixed[] A map of progress per task. Array key is task FQN and current progress is value.
      */
-    public function getProgressByTask(): array
+    public function getProgressByTask()
     {
         return $this->taskProgressMap;
     }
@@ -250,14 +254,14 @@ public function getProgressByTask(): array
      *
      * @return Task Created task.
      */
-    abstract protected function createSubTask(string $taskKey): Task;
+    abstract protected function createSubTask($taskKey);
 
     /**
      * Returns active task.
      *
      * @return Task|null Active task if any; otherwise, NULL.
      */
-    protected function getActiveTask(): ?Task
+    protected function getActiveTask()
     {
         $task = null;
         foreach ($this->taskProgressMap as $taskKey => $taskProgress) {
@@ -282,7 +286,7 @@ protected function getActiveTask(): ?Task
      *
      * @return Task An instance of task for given FQN.
      */
-    protected function getSubTask(string $taskKey): Task
+    protected function getSubTask(string $taskKey)
     {
         if (empty($this->tasks[$taskKey])) {
             $this->tasks[$taskKey] = $this->createSubTask($taskKey);
@@ -294,8 +298,10 @@ protected function getSubTask(string $taskKey): Task
 
     /**
      * Registers "report progress" and "report alive" events to all sub tasks.
+     *
+     * @return void
      */
-    protected function registerSubTasksEvents(): void
+    protected function registerSubTasksEvents()
     {
         foreach ($this->tasks as $key => $task) {
             $this->registerSubTaskEvents($key);
@@ -306,8 +312,10 @@ protected function registerSubTasksEvents(): void
      * Registers "report progress" and "report alive" events to a sub task.
      *
      * @param string $taskKey KeyA Task for which to register listener.
+     *
+     * @return void
      */
-    protected function registerSubTaskEvents(string $taskKey): void
+    protected function registerSubTaskEvents($taskKey)
     {
         $task = $this->tasks[$taskKey];
         $task->setExecutionId($this->getExecutionId());
@@ -320,8 +328,10 @@ protected function registerSubTaskEvents(string $taskKey): void
      *
      * @param float $subTaskProgress Progress for current sub task.
      * @param string $subTaskKey FQN of current task.
+     *
+     * @return void
      */
-    protected function calculateProgress(float $subTaskProgress, string $subTaskKey): void
+    protected function calculateProgress($subTaskProgress, $subTaskKey)
     {
         // set current task progress to overall map
         $this->taskProgressMap[$subTaskKey] = $subTaskProgress;
@@ -343,7 +353,7 @@ protected function calculateProgress(float $subTaskProgress, string $subTaskKey)
      *
      * @return bool TRUE if all tasks are completed; otherwise, FALSE.
      */
-    protected function isProcessCompleted(): bool
+    protected function isProcessCompleted()
     {
         foreach (array_keys($this->tasksProgressShare) as $subTaskKey) {
             if ($this->taskProgressMap[$subTaskKey] < 100) {
@@ -358,8 +368,10 @@ protected function isProcessCompleted(): bool
      * Registers "report alive" event listener so that this composite task can broadcast event.
      *
      * @param Task $task A Task for which to register listener.
+     *
+     * @return void
      */
-    protected function registerReportAliveEvent(Task $task): void
+    protected function registerReportAliveEvent(Task $task)
     {
         $self = $this;
 
@@ -375,8 +387,10 @@ function () use ($self) {
      * Registers "report progress" event listener so that this composite task can calculate and report overall progress.
      *
      * @param string $taskKey A Task for which to register listener.
+     *
+     * @return void
      */
-    protected function registerReportProgressEvent(string $taskKey): void
+    protected function registerReportProgressEvent($taskKey)
     {
         $self = $this;
         $task = $this->tasks[$taskKey];
@@ -395,9 +409,11 @@ function (TaskProgressEvent $event) use ($self, $taskKey) {
      *
      * @param Task $activeTask
      *
+     * @return void
+     *
      * @throws AbortTaskExecutionException
      */
-    protected function executeSubTask(Task $activeTask): void
+    protected function executeSubTask(Task $activeTask)
     {
         $activeTask->execute();
     }
diff --git a/src/Infrastructure/TaskExecution/Events/QueueItemAbortedEvent.php b/src/Infrastructure/TaskExecution/Events/QueueItemAbortedEvent.php
index 68c9fab..679133a 100644
--- a/src/Infrastructure/TaskExecution/Events/QueueItemAbortedEvent.php
+++ b/src/Infrastructure/TaskExecution/Events/QueueItemAbortedEvent.php
@@ -22,7 +22,7 @@ class QueueItemAbortedEvent extends BaseQueueItemEvent
      * @param QueueItem $queueItem
      * @param string $abortDescription
      */
-    public function __construct(QueueItem $queueItem, string $abortDescription)
+    public function __construct(QueueItem $queueItem, $abortDescription)
     {
         parent::__construct($queueItem);
         $this->abortDescription = $abortDescription;
diff --git a/src/Infrastructure/TaskExecution/Interfaces/AsyncProcessService.php b/src/Infrastructure/TaskExecution/Interfaces/AsyncProcessService.php
index f81c82b..8346ccd 100644
--- a/src/Infrastructure/TaskExecution/Interfaces/AsyncProcessService.php
+++ b/src/Infrastructure/TaskExecution/Interfaces/AsyncProcessService.php
@@ -21,14 +21,18 @@ interface AsyncProcessService
      *
      * @param Runnable $runner Runner that should be started async
      *
+     * @return void
+     *
      * @throws ProcessStarterSaveException
      */
-    public function start(Runnable $runner): void;
+    public function start(Runnable $runner);
 
     /**
      * Runs a process with provided identifier.
      *
      * @param string $guid Identifier of process.
+     *
+     * @return void
      */
-    public function runProcess($guid): void;
+    public function runProcess($guid);
 }
diff --git a/src/Infrastructure/TaskExecution/Interfaces/Runnable.php b/src/Infrastructure/TaskExecution/Interfaces/Runnable.php
index 016a1b2..78a7d49 100644
--- a/src/Infrastructure/TaskExecution/Interfaces/Runnable.php
+++ b/src/Infrastructure/TaskExecution/Interfaces/Runnable.php
@@ -13,6 +13,8 @@ interface Runnable extends Serializable
 {
     /**
      * Starts runnable run logic
+     *
+     * @return void
      */
-    public function run(): void;
+    public function run();
 }
diff --git a/src/Infrastructure/TaskExecution/Interfaces/TaskRunnerManager.php b/src/Infrastructure/TaskExecution/Interfaces/TaskRunnerManager.php
index a0fcbfa..359d033 100644
--- a/src/Infrastructure/TaskExecution/Interfaces/TaskRunnerManager.php
+++ b/src/Infrastructure/TaskExecution/Interfaces/TaskRunnerManager.php
@@ -13,11 +13,15 @@ interface TaskRunnerManager
 
     /**
      * Halts task runner.
+     *
+     * @return void
      */
-    public function halt(): void;
+    public function halt();
 
     /**
      * Resumes task execution.
+     *
+     * @return void
      */
-    public function resume(): void;
+    public function resume();
 }
diff --git a/src/Infrastructure/TaskExecution/Interfaces/TaskRunnerStatusStorage.php b/src/Infrastructure/TaskExecution/Interfaces/TaskRunnerStatusStorage.php
index 600a742..cfbdd3b 100644
--- a/src/Infrastructure/TaskExecution/Interfaces/TaskRunnerStatusStorage.php
+++ b/src/Infrastructure/TaskExecution/Interfaces/TaskRunnerStatusStorage.php
@@ -24,7 +24,7 @@ interface TaskRunnerStatusStorage
      * @return TaskRunnerStatus Current runner status
      * @throws TaskRunnerStatusStorageUnavailableException When task storage is not available
      */
-    public function getStatus(): TaskRunnerStatus;
+    public function getStatus();
 
     /**
      * Sets status of task runner to provided status.
@@ -32,9 +32,11 @@ public function getStatus(): TaskRunnerStatus;
      *
      * @param TaskRunnerStatus $status
      *
+     * @return void
+     *
      * @throws TaskRunnerStatusChangeException Thrown when setting status operation fails because:
      *      - Trying to set new task status to new nonempty guid but currently set guid is not empty
      * @throws TaskRunnerStatusStorageUnavailableException When task storage is not available
      */
-    public function setStatus(TaskRunnerStatus $status): void;
+    public function setStatus(TaskRunnerStatus $status);
 }
diff --git a/src/Infrastructure/TaskExecution/Interfaces/TaskRunnerWakeup.php b/src/Infrastructure/TaskExecution/Interfaces/TaskRunnerWakeup.php
index 0064c84..c1b8ec3 100644
--- a/src/Infrastructure/TaskExecution/Interfaces/TaskRunnerWakeup.php
+++ b/src/Infrastructure/TaskExecution/Interfaces/TaskRunnerWakeup.php
@@ -16,6 +16,8 @@ interface TaskRunnerWakeup
 
     /**
      * Wakes up TaskRunner instance asynchronously if active instance is not already running.
+     *
+     * @return void
      */
-    public function wakeup(): void;
+    public function wakeup();
 }
diff --git a/src/Infrastructure/TaskExecution/Process.php b/src/Infrastructure/TaskExecution/Process.php
index 96b7cd8..bd4843f 100644
--- a/src/Infrastructure/TaskExecution/Process.php
+++ b/src/Infrastructure/TaskExecution/Process.php
@@ -38,9 +38,11 @@ class Process extends Entity
      *
      * @param mixed[] $data Raw array data with keys 'id', 'guid' and 'runner'.
      *
+     * @return void
+     *
      * @throws InvalidArgumentException In case when @see $data does not have all needed keys.
      */
-    public function inflate(array $data): void
+    public function inflate(array $data)
     {
         if (!isset($data['guid'], $data['runner'])) {
             throw new InvalidArgumentException('Data array needs to have "guid" and "runner" keys.');
@@ -56,7 +58,7 @@ public function inflate(array $data): void
      *
      * @return mixed[] Entity in array format.
      */
-    public function toArray(): array
+    public function toArray()
     {
         $data = parent::toArray();
         $data['guid'] = $this->getGuid();
@@ -70,7 +72,7 @@ public function toArray(): array
      *
      * @return EntityConfiguration
      */
-    public function getConfig(): EntityConfiguration
+    public function getConfig()
     {
         $indexMap = new IndexMap();
         $indexMap->addStringIndex('guid');
@@ -83,7 +85,7 @@ public function getConfig(): EntityConfiguration
      *
      * @return string Guid.
      */
-    public function getGuid(): string
+    public function getGuid()
     {
         return $this->guid;
     }
@@ -92,8 +94,10 @@ public function getGuid(): string
      * Sets Guid.
      *
      * @param string $guid Guid.
+     *
+     * @return void
      */
-    public function setGuid(string $guid): void
+    public function setGuid($guid)
     {
         $this->guid = $guid;
     }
@@ -103,7 +107,7 @@ public function setGuid(string $guid): void
      *
      * @return Runnable Runner.
      */
-    public function getRunner(): Runnable
+    public function getRunner()
     {
         return $this->runner;
     }
@@ -112,8 +116,10 @@ public function getRunner(): Runnable
      * Sets Runner.
      *
      * @param Runnable $runner Runner.
+     *
+     * @return void
      */
-    public function setRunner(Runnable $runner): void
+    public function setRunner(Runnable $runner)
     {
         $this->runner = $runner;
     }
diff --git a/src/Infrastructure/TaskExecution/QueueItemStarter.php b/src/Infrastructure/TaskExecution/QueueItemStarter.php
index c051700..65bbebb 100644
--- a/src/Infrastructure/TaskExecution/QueueItemStarter.php
+++ b/src/Infrastructure/TaskExecution/QueueItemStarter.php
@@ -61,7 +61,7 @@ public function __construct($queueItemId)
      * @return Serializable
      *      Instance of serialized object.
      */
-    public static function fromArray(array $array): Serializable
+    public static function fromArray(array $array)
     {
         return new static($array['queue_item_id']);
     }
diff --git a/src/Infrastructure/TaskExecution/Task.php b/src/Infrastructure/TaskExecution/Task.php
index cab587c..9533c73 100644
--- a/src/Infrastructure/TaskExecution/Task.php
+++ b/src/Infrastructure/TaskExecution/Task.php
@@ -60,14 +60,16 @@ public function __construct()
     /**
      * Runs task logic.
      *
+     * @return void
+     *
      * @throws AbortTaskExecutionException
      */
-    abstract public function execute(): void;
+    abstract public function execute();
 
     /**
      * @inheritdoc
      */
-    public function serialize(): ?string
+    public function serialize()
     {
         return Serializer::serialize(array());
     }
@@ -84,7 +86,7 @@ public function unserialize($data)
     /**
      * @inheritDoc
      */
-    public static function fromArray(array $array): Serializable
+    public static function fromArray(array $array)
     {
         return new static();
     }
@@ -92,7 +94,7 @@ public static function fromArray(array $array): Serializable
     /**
      * @inheritDoc
      */
-    public function toArray(): array
+    public function toArray()
     {
         return array();
     }
@@ -115,10 +117,12 @@ public function getPriority(): int
      *
      * @param float|int $progressPercent
      *
+     * @return void
+     *
      * @throws InvalidArgumentException In case when progress percent is outside of 0 - 100 boundaries or not an float
      * @see    TaskProgressEvent and defers next @see AliveAnnouncedTaskEvent.
      */
-    public function reportProgress($progressPercent): void
+    public function reportProgress($progressPercent)
     {
         if (!is_int($progressPercent) && !is_float($progressPercent)) {
             throw new InvalidArgumentException('Progress percentage must be value integer or float value');
@@ -138,9 +142,11 @@ public function reportProgress($progressPercent): void
      *
      * @param boolean $force
      *
+     * @return void
+     *
      * @see AliveAnnouncedTaskEvent.
      */
-    public function reportAlive(bool $force = false): void
+    public function reportAlive($force = false)
     {
         /**
          * @var TimeProvider $timeProvider
@@ -161,7 +167,7 @@ public function reportAlive(bool $force = false): void
      *
      * @return int Max inactivity period for a task in seconds.
      */
-    public function getMaxInactivityPeriod(): int
+    public function getMaxInactivityPeriod()
     {
         $configurationValue = $this->getConfigService()->getMaxTaskInactivityPeriod();
 
@@ -174,7 +180,7 @@ public function getMaxInactivityPeriod(): int
      *
      * @return string FQN of the task.
      */
-    public function getType(): string
+    public function getType()
     {
         return static::getClassName();
     }
@@ -184,7 +190,7 @@ public function getType(): string
      *
      * @return string FQN of the task.
      */
-    public static function getClassName(): string
+    public static function getClassName()
     {
         $namespaceParts = explode('\\', get_called_class());
         $name = end($namespaceParts);
@@ -201,15 +207,17 @@ public static function getClassName(): string
      *
      * @return bool TRUE if task can be reconfigured; otherwise, FALSE.
      */
-    public function canBeReconfigured(): bool
+    public function canBeReconfigured()
     {
         return false;
     }
 
     /**
      * Reconfigures the task.
+     *
+     * @return void
      */
-    public function reconfigure(): void
+    public function reconfigure()
     {
     }
 
@@ -227,24 +235,30 @@ public function getExecutionId()
      * Sets Execution id.
      *
      * @param int|string $executionId Execution id.
+     *
+     * @return void
      */
-    public function setExecutionId($executionId): void
+    public function setExecutionId($executionId)
     {
         $this->executionId = $executionId;
     }
 
     /**
      * Cleans up resources upon failure.
+     *
+     * @return void
      */
-    public function onFail(): void
+    public function onFail()
     {
         // Extension stub.
     }
 
     /**
      * Cleans up resources upon abort.
+     *
+     * @return void
      */
-    public function onAbort(): void
+    public function onAbort()
     {
         // Extension stub.
     }
@@ -256,7 +270,7 @@ public function onAbort(): void
      *
      * @return int Base points representation of percentage.
      */
-    protected function percentToBasePoints(float $percentValue): int
+    protected function percentToBasePoints($percentValue)
     {
         return (int)round($percentValue * 100, 2);
     }
diff --git a/src/Infrastructure/TaskExecution/TaskRunnerStarter.php b/src/Infrastructure/TaskExecution/TaskRunnerStarter.php
index 3cd8b8f..6f5d742 100644
--- a/src/Infrastructure/TaskExecution/TaskRunnerStarter.php
+++ b/src/Infrastructure/TaskExecution/TaskRunnerStarter.php
@@ -70,7 +70,7 @@ public function __construct($guid)
      * @return Serializable
      *      Instance of serialized object.
      */
-    public static function fromArray(array $array): Serializable
+    public static function fromArray(array $array)
     {
         return new static($array['guid']);
     }
diff --git a/tests/Infrastructure/Common/TestComponents/ORM/MemoryRepository.php b/tests/Infrastructure/Common/TestComponents/ORM/MemoryRepository.php
index b977d47..5e72305 100644
--- a/tests/Infrastructure/Common/TestComponents/ORM/MemoryRepository.php
+++ b/tests/Infrastructure/Common/TestComponents/ORM/MemoryRepository.php
@@ -170,11 +170,9 @@ public static function getClassName()
     }
 
     /**
-     * Sets repository entity
-     *
-     * @param string $entityClass
+     * @inheritdoc
      */
-    public function setEntityClass(string $entityClass): void
+    public function setEntityClass($entityClass)
     {
         $this->entityClass = $entityClass;
     }
diff --git a/tests/Infrastructure/Common/TestComponents/TaskExecution/AbortTask.php b/tests/Infrastructure/Common/TestComponents/TaskExecution/AbortTask.php
index a6263d6..0d8bf05 100644
--- a/tests/Infrastructure/Common/TestComponents/TaskExecution/AbortTask.php
+++ b/tests/Infrastructure/Common/TestComponents/TaskExecution/AbortTask.php
@@ -21,7 +21,7 @@ public function execute(): void
     /**
      * @inheritDoc
      */
-    public static function fromArray(array $array): Serializable
+    public static function fromArray(array $array)
     {
         return new static();
     }
diff --git a/tests/Infrastructure/Common/TestComponents/TaskExecution/FakeRunnable.php b/tests/Infrastructure/Common/TestComponents/TaskExecution/FakeRunnable.php
index 605e670..61d77f0 100644
--- a/tests/Infrastructure/Common/TestComponents/TaskExecution/FakeRunnable.php
+++ b/tests/Infrastructure/Common/TestComponents/TaskExecution/FakeRunnable.php
@@ -40,7 +40,7 @@ public function unserialize($serialized)
     /**
      * @inheritDoc
      */
-    public static function fromArray(array $array): Serializable
+    public static function fromArray(array $array)
     {
         $instance = new self($array['testProperty']);
 
diff --git a/tests/Infrastructure/Common/TestComponents/TaskExecution/FooTask.php b/tests/Infrastructure/Common/TestComponents/TaskExecution/FooTask.php
index a57a9b7..8faa784 100644
--- a/tests/Infrastructure/Common/TestComponents/TaskExecution/FooTask.php
+++ b/tests/Infrastructure/Common/TestComponents/TaskExecution/FooTask.php
@@ -141,7 +141,7 @@ public function reconfigure(): void
         $this->methodsCallCount['reconfigure']++;
     }
 
-    public function canBeReconfigured(): bool
+    public function canBeReconfigured()
     {
         return true;
     }