diff --git a/src/app/DataMigrator/EWS/Appointment.php b/src/app/DataMigrator/EWS/Appointment.php
index 6256026f..98799ab2 100644
--- a/src/app/DataMigrator/EWS/Appointment.php
+++ b/src/app/DataMigrator/EWS/Appointment.php
@@ -1,92 +1,92 @@
 <?php
 
 namespace App\DataMigrator\EWS;
 
 use garethp\ews\API;
 use garethp\ews\API\Type;
 
 /**
  * Appointment (calendar event) object handler
  */
 class Appointment extends Item
 {
     const FOLDER_TYPE = 'IPF.Appointment';
     const TYPE        = 'IPM.Appointment';
     const FILE_EXT    = 'ics';
 
 
     /**
      * Get GetItem request parameters
      */
     protected function getItemRequest(): array
     {
         $request = parent::getItemRequest();
 
         // Request IncludeMimeContent as it's not included by default
         $request['ItemShape']['IncludeMimeContent'] = true;
 
         // Get UID property, it's not included in the Default set
         // FIXME: How to add the property to the set, not replace the whole set
         $request['ItemShape']['AdditionalProperties']['FieldURI'] = ['FieldURI' => 'calendar:UID'];
 
         return $request;
     }
 
     /**
      * Process event object
      */
-    protected function processItem(Type &$item): bool
+    protected function processItem(Type $item): bool
     {
         // Decode MIME content
         // TODO: Maybe find less-hacky way
         $content = $item->getMimeContent();
         $ical = base64_decode((string) $content);
 
         // Inject attachment bodies into the iCalendar content
         // Calendar event attachments are exported as:
         // ATTACH:CID:81490FBA13A3DC2BF071B894C96B44BA51BEAAED@eurprd05.prod.outlook.com
         if ($item->getHasAttachments()) {
             // FIXME: I've tried hard and no matter what ContentId property is always empty
             //        This means we can't match the CID from iCalendar with the attachment.
             //        That's why we'll just remove all ATTACH:CID:... occurrences
             //        and inject attachments to the main event
             $ical = preg_replace('/\r\nATTACH:CID:[^\r]+\r\n(\r\n [^\r\n]*)?/', '', $ical);
 
             foreach ((array) $item->getAttachments()->getFileAttachment() as $attachment) {
                 $_attachment = $this->getAttachment($attachment);
 
                 // FIXME: This is imo inconsistence on php-ews side that MimeContent
                 //        is base64 encoded, but Content isn't
                 // TODO: We should not do it in memory to not exceed the memory limit
                 $body = base64_encode($_attachment->getContent());
                 $body = rtrim(chunk_split($body, 74, "\r\n "), ' ');
 
                 $ctype = $_attachment->getContentType();
 
                 // Inject the attachment at the end of the first VEVENT block
                 // TODO: We should not do it in memory to not exceed the memory limit
                 $append = "ATTACH;VALUE=BINARY;ENCODING=BASE64;FMTTYPE={$ctype}:\r\n {$body}";
                 $pos = strpos($ical, "\r\nEND:VEVENT");
                 $ical = substr_replace($ical, $append, $pos + 2, 0);
             }
         }
 
         // TODO: Maybe find less-hacky way
         $item->getMimeContent()->_ = $ical;
 
         return true;
     }
 
     /**
      * Get Item UID (Generate a new one if needed)
      */
     protected function getUID(Type $item): string
     {
         if ($this->uid === null) {
             // Only appointments have UID property
             $this->uid = $item->getUID();
         }
 
         return $this->uid;
     }
 }
diff --git a/src/app/DataMigrator/EWS/Contact.php b/src/app/DataMigrator/EWS/Contact.php
index e96fe532..6225ca1a 100644
--- a/src/app/DataMigrator/EWS/Contact.php
+++ b/src/app/DataMigrator/EWS/Contact.php
@@ -1,49 +1,49 @@
 <?php
 
 namespace App\DataMigrator\EWS;
 
 use garethp\ews\API\Type;
 
 /**
  * Contact object handler
  */
 class Contact extends Item
 {
     const FOLDER_TYPE = 'IPF.Contact';
     const TYPE        = 'IPM.Contact';
     const FILE_EXT    = 'vcf';
 
     /**
      * Get GetItem request parameters
      */
     protected function getItemRequest(): array
     {
         $request = parent::getItemRequest();
 
         // Request IncludeMimeContent as it's not included by default
         $request['ItemShape']['IncludeMimeContent'] = true;
 
         return $request;
     }
 
     /**
      * Process contact object
      */
-    protected function processItem(Type &$item): bool
+    protected function processItem(Type $item): bool
     {
         // Decode MIME content
         $vcard = base64_decode((string) $item->getMimeContent());
 
         // Inject UID to the vCard
         $uid = $this->getUID($item);
         $vcard = str_replace("BEGIN:VCARD", "BEGIN:VCARD\r\nUID:{$uid}", $vcard);
 
         // Note: Looks like PHOTO property is exported properly, so we
         //       don't have to handle attachments as we do for calendar items
 
         // TODO: Maybe find less-hacky way
         $item->getMimeContent()->_ = $vcard;
 
         return true;
     }
 }
diff --git a/src/app/DataMigrator/EWS/DistList.php b/src/app/DataMigrator/EWS/DistList.php
index 4cbbd45f..37570127 100644
--- a/src/app/DataMigrator/EWS/DistList.php
+++ b/src/app/DataMigrator/EWS/DistList.php
@@ -1,64 +1,64 @@
 <?php
 
 namespace App\DataMigrator\EWS;
 
 use garethp\ews\API\Type;
 
 /**
  * Distribution List object handler
  */
 class DistList extends Item
 {
     const FOLDER_TYPE = 'IPF.Contact';
     const TYPE        = 'IPM.DistList';
     const FILE_EXT    = 'vcf';
 
     /**
      * Convert distribution list object to vCard
      */
-    protected function processItem(Type &$item): bool
+    protected function processItem(Type $item): bool
     {
         // Groups (Distribution Lists) are not exported in vCard format, they use eml
 
         $data = [
             "UID" => $this->getUID($item),
             "KIND" => "group",
             "FN" => $item->getDisplayName(),
             "REV;VALUE=DATE-TIME" => $item->getLastModifiedTime(),
         ];
 
         $vcard = "BEGIN:VCARD\r\nVERSION:4.0\r\nPRODID:Kolab EWS DataMigrator\r\n";
 
         foreach ($data as $key => $value) {
             // TODO: value wrapping/escaping
             $vcard .= "{$key}:{$value}\r\n";
         }
 
         // Process list members
         // Note: The fact that getMembers() returns stdClass is probably a bug in php-ews
         foreach ($item->getMembers()->Member as $member) {
             $mailbox = $member->getMailbox();
             $mailto = $mailbox->getEmailAddress();
             $name = $mailbox->getName();
 
             // FIXME: Investigate if mailto: members are handled properly by Kolab
             //        or we need to use MEMBER:urn:uuid:9bd97510-9dbb-4810-a144-6180962df5e0 syntax
             //        But do not forget lists can have members that are not contacts
 
             if ($mailto) {
                 if ($name && $name != $mailto) {
                     $mailto = urlencode(sprintf('"%s" <%s>', addcslashes($name, '"'), $mailto));
                 }
 
                 $vcard .= "MEMBER:mailto:{$mailto}\r\n";
             }
         }
 
         $vcard .= "END:VCARD";
 
         // TODO: Maybe find less-hacky way
         $item->setMimeContent((new Type\MimeContentType)->set('_', $vcard));
 
         return true;
     }
 }
diff --git a/src/app/DataMigrator/EWS/Item.php b/src/app/DataMigrator/EWS/Item.php
index 41786d0c..1dec3996 100644
--- a/src/app/DataMigrator/EWS/Item.php
+++ b/src/app/DataMigrator/EWS/Item.php
@@ -1,134 +1,134 @@
 <?php
 
 namespace App\DataMigrator\EWS;
 
 use App\DataMigrator\EWS;
 
 use garethp\ews\API;
 use garethp\ews\API\Type;
 
 /**
  * Abstraction for object handlers
  */
 abstract class Item
 {
     /** @var EWS Data migrator object */
     protected $engine;
 
     /** @var array Current folder data */
     protected $folder;
 
     /** @var string Current item UID */
     protected $uid;
 
 
     /**
      * Object constructor
      */
     public function __construct(EWS $engine, array $folder)
     {
         $this->engine = $engine;
         $this->folder = $folder;
     }
 
     /**
      * Factory method.
      * Returns object suitable to handle specified item type.
      */
     public static function factory(EWS $engine, Type $item, array $folder)
     {
         $item_class = str_replace('IPM.', '', $item->getItemClass());
         $item_class = "\App\DataMigrator\EWS\\{$item_class}";
 
         if (class_exists($item_class)) {
             return new $item_class($engine, $folder);
         }
     }
 
     /**
      * Synchronize specified object
      */
     public function syncItem(Type $item): void
     {
         // Fetch the item
         $item = $this->engine->api->getItem($item->getItemId(), $this->getItemRequest());
 
         $uid = $this->getUID($item);
 
         $this->engine->debug("* Saving item {$uid}...");
 
         // Apply type-specific format converters
         if ($this->processItem($item) === false) {
             return;
         }
 
         $uid = preg_replace('/[^a-zA-Z0-9_:@-]/', '', $uid);
 
         $location = $this->folder['location'];
 
         if (!file_exists($location)) {
             mkdir($location, 0740, true);
         }
 
         $location .= '/' . $uid . '.' . $this::FILE_EXT;
 
         file_put_contents($location, (string) $item->getMimeContent());
     }
 
     /**
      * Item conversion code
      */
-    abstract protected function processItem(Type &$item): bool;
+    abstract protected function processItem(Type $item): bool;
 
     /**
      * Get GetItem request parameters
      */
     protected function getItemRequest(): array
     {
         $request = [
             'ItemShape' => [
                 // Reqest default set of properties
                 'BaseShape' => 'Default',
                 // Additional properties, e.g. LastModifiedTime
                 // FIXME: How to add multiple properties here?
                 'AdditionalProperties' => [
                     'FieldURI' => ['FieldURI' => 'item:LastModifiedTime'],
                 ]
             ]
         ];
 
         return $request;
     }
 
     /**
      * Fetch attachment object from Exchange
      */
     protected function getAttachment(Type\FileAttachmentType $attachment)
     {
         $request = [
             'AttachmentIds' => [
                 $attachment->getAttachmentId()->toXmlObject()
             ],
             'AttachmentShape' => [
                 'IncludeMimeContent' => true,
             ]
         ];
 
         return $this->engine->api->getClient()->GetAttachment($request);
     }
 
     /**
      * Get Item UID (Generate a new one if needed)
      */
     protected function getUID(Type $item): string
     {
         if ($this->uid === null) {
             // We should generate an UID for objects that do not have it
             // and inject it into the output file
             // FIXME: Should we use e.g. md5($itemId->getId()) instead?
             $this->uid = \App\Utils::uuidStr();
         }
 
         return $this->uid;
     }
 }
diff --git a/src/app/DataMigrator/EWS/Task.php b/src/app/DataMigrator/EWS/Task.php
index 10a50e0d..73054061 100644
--- a/src/app/DataMigrator/EWS/Task.php
+++ b/src/app/DataMigrator/EWS/Task.php
@@ -1,111 +1,111 @@
 <?php
 
 namespace App\DataMigrator\EWS;
 
 use garethp\ews\API\Type;
 
 /**
  * Task objects handler
  */
 class Task extends Item
 {
     const FOLDER_TYPE = 'IPF.Task';
     const TYPE        = 'IPM.Task';
     const FILE_EXT    = 'ics';
 
     /**
      * Get GetItem request parameters
      */
     protected function getItemRequest(): array
     {
         $request = parent::getItemRequest();
 
         // For tasks we need all properties
         $request['ItemShape']['BaseShape'] = 'AllProperties';
 
         return $request;
     }
 
     /**
      * Process task object
      */
-    protected function processItem(Type &$item): bool
+    protected function processItem(Type $item): bool
     {
         // Tasks are exported as Email messages in useless format
         // (does not contain all relevant properties)
         // We'll build the iCalendar using properties directly
         // TODO: This probably should be done with sabre-vobject
 
         $data = [
             "UID" => $this->getUID($item),
             "DTSTAMP;VALUE=DATE-TIME" => $item->getLastModifiedTime(),
             "CREATED;VALUE=DATE-TIME" => $item->getDateTimeCreated(),
             "SEQUENCE" => '0', // TODO
             "SUMMARY" => $item->getSubject(),
             "DESCRIPTION" => (string) $item->getBody(),
             "PERCENT-COMPLETE" => intval($item->getPercentComplete()),
             "STATUS" => strtoupper($item->getStatus()),
         ];
 
         if ($dueDate = $item->getDueDate()) {
             $data["DUE:VALUE=DATE-TIME"] = $dueDate;
         }
 
         if ($startDate = $item->getStartDate()) {
             $data["DTSTART:VALUE=DATE-TIME"] = $startDate;
         }
 
         if (($categories = $item->getCategories()) && $categories->String) {
             $data["CATEGORIES"] = $categories->String;
         }
 
         if ($sensitivity = $item->getSensitivity()) {
             $sensitivity_map = [
                 'CONFIDENTIAL' => 'CONFIDENTIAL',
                 'NORMAL' => 'PUBLIC',
                 'PERSONAL' => 'PUBLIC',
                 'PRIVATE' => 'PRIVATE',
             ];
 
             $data['CLASS'] = $sensitivity_map[strtoupper($sensitivity)] ?: 'PUBLIC';
         }
 
         // TODO: VTIMEZONE, VALARM, ORGANIZER, ATTENDEE, RRULE,
         // TODO: PRIORITY (Importance) - not used by Kolab
         // ReminderDueBy, ReminderIsSet, IsRecurring, Owner, Recurrence
 
         $ical = "BEGIN:VCALENDAR\r\nMETHOD:PUBLISH\r\nVERSION:2.0\r\nPRODID:Kolab EWS DataMigrator\r\nBEGIN:VTODO\r\n";
 
         foreach ($data as $key => $value) {
             // TODO: value wrapping/escaping
             $ical .= "{$key}:{$value}\r\n";
         }
 
         // Attachments
         if ($item->getHasAttachments()) {
             foreach ((array) $item->getAttachments()->getFileAttachment() as $attachment) {
                 $_attachment = $this->getAttachment($attachment);
 
                 // FIXME: This is imo inconsistence on php-ews side that MimeContent
                 //        is base64 encoded, but Content isn't
                 // TODO: We should not do it in memory to not exceed the memory limit
                 $body = base64_encode($_attachment->getContent());
                 $body = rtrim(chunk_split($body, 74, "\r\n "), ' ');
 
                 $ctype = $_attachment->getContentType();
 
                 // Inject the attachment at the end of the VTODO block
                 // TODO: We should not do it in memory to not exceed the memory limit
                 $ical .= "ATTACH;VALUE=BINARY;ENCODING=BASE64;FMTTYPE={$ctype}:\r\n {$body}\r\n";
             }
         }
 
         $ical .= "END:VEVENT\r\n";
         $ical .= "END:VCALENDAR";
 
         // TODO: Maybe find less-hacky way
         $item->setMimeContent((new Type\MimeContentType)->set('_', $ical));
 
         return true;
     }
 }