diff --git a/src/API/Type/ArrayOfFoldersType.php b/src/API/Type/ArrayOfFoldersType.php
index 8ab70fde..3aeef6a8 100644
--- a/src/API/Type/ArrayOfFoldersType.php
+++ b/src/API/Type/ArrayOfFoldersType.php
@@ -86,23 +86,23 @@ public function getAllFolders()
         return $this->allFolders;
     }
 
-    public function count()
+    public function count(): int
     {
         return count($this->getAllFolders());
     }
 
-    public function offsetExists($offset)
+    public function offsetExists($offset): bool
     {
         return isset($this->getAllFolders()[$offset]);
     }
 
-    public function offsetGet($offset)
+    public function offsetGet($offset): mixed
     {
         $this->getAllFolders();
         return isset($this->allFolders[$offset]) ? $this->allFolders[$offset] : null;
     }
 
-    public function offsetSet($offset, $value)
+    public function offsetSet($offset, $value): void
     {
         $this->getAllFolders();
 
@@ -113,13 +113,13 @@ public function offsetSet($offset, $value)
         }
     }
 
-    public function offsetUnset($offset)
+    public function offsetUnset($offset): void
     {
         $this->getAllFolders();
         unset($this->allFolders[$offset]);
     }
 
-    public function getIterator()
+    public function getIterator(): \Traversable
     {
         $this->getAllFolders();
         return new \ArrayIterator($this->allFolders);
diff --git a/src/API/Type/ArrayOfRealItemsType.php b/src/API/Type/ArrayOfRealItemsType.php
index a9d18e2a..70e410d2 100644
--- a/src/API/Type/ArrayOfRealItemsType.php
+++ b/src/API/Type/ArrayOfRealItemsType.php
@@ -117,23 +117,23 @@ public function getItems()
         return $this->itemsArray;
     }
 
-    public function count()
+    public function count(): int
     {
         return count($this->getItems());
     }
 
-    public function offsetExists($offset)
+    public function offsetExists($offset): bool
     {
         return isset($this->getItems()[$offset]);
     }
 
-    public function offsetGet($offset)
+    public function offsetGet($offset): mixed
     {
         $this->getItems();
         return isset($this->itemsArray[$offset]) ? $this->itemsArray[$offset] : null;
     }
 
-    public function offsetSet($offset, $value)
+    public function offsetSet($offset, $value): void
     {
         $this->getItems();
 
@@ -144,13 +144,13 @@ public function offsetSet($offset, $value)
         }
     }
 
-    public function offsetUnset($offset)
+    public function offsetUnset($offset): void
     {
         $this->getItems();
         unset($this->itemsArray[$offset]);
     }
 
-    public function getIterator()
+    public function getIterator(): \Traversable
     {
         $this->getItems();
         return new \ArrayIterator($this->itemsArray);
diff --git a/src/API/Type/FindFolderParentType.php b/src/API/Type/FindFolderParentType.php
index 1fe10fe5..bf6dbdab 100644
--- a/src/API/Type/FindFolderParentType.php
+++ b/src/API/Type/FindFolderParentType.php
@@ -53,22 +53,22 @@ class FindFolderParentType extends Type implements Countable, ArrayAccess, Itera
      */
     protected $folders = null;
 
-    public function count()
+    public function count(): int
     {
         return count($this->folders);
     }
 
-    public function offsetExists($offset)
+    public function offsetExists($offset): bool
     {
         return isset($this->folders[$offset]);
     }
 
-    public function offsetGet($offset)
+    public function offsetGet($offset): mixed
     {
         return isset($this->folders[$offset]) ? $this->folders[$offset] : null;
     }
 
-    public function offsetSet($offset, $value)
+    public function offsetSet($offset, $value): void
     {
         if (is_null($offset)) {
             array_push($this->folders, $value);
@@ -77,12 +77,12 @@ public function offsetSet($offset, $value)
         }
     }
 
-    public function offsetUnset($offset)
+    public function offsetUnset($offset): void
     {
         unset($this->folders[$offset]);
     }
 
-    public function getIterator()
+    public function getIterator(): \Traversable
     {
         return new \ArrayIterator($this->folders->getIterator());
     }
diff --git a/src/API/Type/FindItemParentType.php b/src/API/Type/FindItemParentType.php
index c3e84147..eacf9973 100644
--- a/src/API/Type/FindItemParentType.php
+++ b/src/API/Type/FindItemParentType.php
@@ -58,24 +58,24 @@ class FindItemParentType extends Type implements Countable, ArrayAccess, Iterato
      */
     protected $lastRequest = null;
 
-    public function count()
+    public function count(): int
     {
         return count($this->items);
     }
 
-    public function offsetExists($offset)
+    public function offsetExists($offset): bool
     {
         $arrayAccessName = ($this->items != null ? 'items' : 'groups');
         return isset($this->{$arrayAccessName}[$offset]);
     }
 
-    public function offsetGet($offset)
+    public function offsetGet($offset): mixed
     {
         $arrayAccessName = ($this->items != null ? 'items' : 'groups');
         return isset($this->{$arrayAccessName}[$offset]) ? $this->{$arrayAccessName}[$offset] : null;
     }
 
-    public function offsetSet($offset, $value)
+    public function offsetSet($offset, $value): void
     {
         $arrayAccessName = ($this->items != null ? 'items' : 'groups');
 
@@ -86,13 +86,13 @@ public function offsetSet($offset, $value)
         }
     }
 
-    public function offsetUnset($offset)
+    public function offsetUnset($offset): void
     {
         $arrayAccessName = ($this->items != null ? 'items' : 'groups');
         unset($this->{$arrayAccessName}[$offset]);
     }
 
-    public function getIterator()
+    public function getIterator(): \Traversable
     {
         $arrayAccessName = ($this->items != null ? 'items' : 'groups');
         return new \ArrayIterator($this->{$arrayAccessName}->getIterator());
diff --git a/src/API/Type/GroupedItemsType.php b/src/API/Type/GroupedItemsType.php
index 389e0ca6..ecb7da0f 100644
--- a/src/API/Type/GroupedItemsType.php
+++ b/src/API/Type/GroupedItemsType.php
@@ -31,22 +31,22 @@ class GroupedItemsType extends Type implements Countable, ArrayAccess, IteratorA
      */
     protected $groupSummary = null;
 
-    public function count()
+    public function count(): int
     {
         return count($this->items);
     }
 
-    public function offsetExists($offset)
+    public function offsetExists($offset): bool
     {
         return isset($this->items[$offset]);
     }
 
-    public function offsetGet($offset)
+    public function offsetGet($offset): mixed
     {
         return isset($this->items[$offset]) ? $this->items[$offset] : null;
     }
 
-    public function offsetSet($offset, $value)
+    public function offsetSet($offset, $value): void
     {
         if (is_null($offset)) {
             $this->items[] = $value;
@@ -55,12 +55,12 @@ public function offsetSet($offset, $value)
         }
     }
 
-    public function offsetUnset($offset)
+    public function offsetUnset($offset): void
     {
         unset($this->items[$offset]);
     }
 
-    public function getIterator()
+    public function getIterator(): \Traversable
     {
         return new \ArrayIterator($this->items->getIterator());
     }