diff --git a/app/code/Magento/Vault/Plugin/PaymentVaultAttributesLoad.php b/app/code/Magento/Vault/Plugin/PaymentVaultAttributesLoad.php
index 6f859e3353146..810a8c5242da8 100644
--- a/app/code/Magento/Vault/Plugin/PaymentVaultAttributesLoad.php
+++ b/app/code/Magento/Vault/Plugin/PaymentVaultAttributesLoad.php
@@ -59,7 +59,9 @@ public function aroundGetExtensionAttributes(
         $paymentToken = $paymentExtension->getVaultPaymentToken();
         if ($paymentToken === null) {
             $paymentToken = $this->paymentTokenManagement->getByPaymentId($payment->getEntityId());
-            $paymentExtension->setVaultPaymentToken($paymentToken);
+            if ($paymentToken instanceof \Magento\Vault\Api\Data\PaymentTokenInterface) {
+                $paymentExtension->setVaultPaymentToken($paymentToken);
+            }
             $payment->setExtensionAttributes($paymentExtension);
         }
 
diff --git a/lib/internal/Magento/Framework/Api/Code/Generator/ExtensionAttributesGenerator.php b/lib/internal/Magento/Framework/Api/Code/Generator/ExtensionAttributesGenerator.php
index bcc3344e2adac..6fc7791c1dbe9 100644
--- a/lib/internal/Magento/Framework/Api/Code/Generator/ExtensionAttributesGenerator.php
+++ b/lib/internal/Magento/Framework/Api/Code/Generator/ExtensionAttributesGenerator.php
@@ -24,6 +24,11 @@ class ExtensionAttributesGenerator extends \Magento\Framework\Code\Generator\Ent
      */
     protected $config;
 
+    /**
+     * @var \Magento\Framework\Reflection\TypeProcessor
+     */
+    protected $typeProcessor;
+
     /**
      * @var array
      */
@@ -33,6 +38,7 @@ class ExtensionAttributesGenerator extends \Magento\Framework\Code\Generator\Ent
      * Initialize dependencies.
      *
      * @param \Magento\Framework\Api\ExtensionAttribute\Config $config
+     * @param \Magento\Framework\Reflection\TypeProcessor $typeProcessor,
      * @param string|null $sourceClassName
      * @param string|null $resultClassName
      * @param Io $ioObject
@@ -41,6 +47,7 @@ class ExtensionAttributesGenerator extends \Magento\Framework\Code\Generator\Ent
      */
     public function __construct(
         \Magento\Framework\Api\ExtensionAttribute\Config $config,
+        \Magento\Framework\Reflection\TypeProcessor $typeProcessor,
         $sourceClassName = null,
         $resultClassName = null,
         Io $ioObject = null,
@@ -49,6 +56,7 @@ public function __construct(
     ) {
         $sourceClassName .= 'Interface';
         $this->config = $config;
+        $this->typeProcessor = $typeProcessor;
         parent::__construct(
             $sourceClassName,
             $resultClassName,
@@ -90,9 +98,15 @@ protected function _getClassMethods()
                 'body' => "return \$this->_get('{$attributeName}');",
                 'docblock' => ['tags' => [['name' => 'return', 'description' => $attributeType . '|null']]],
             ];
+            $parameters = ['name' => $propertyName];
+            // If the attribute type is a valid type declaration (e.g., interface, class, array) then use it to enforce
+            // constraints on the generated setter methods
+            if ($this->typeProcessor->isValidTypeDeclaration($attributeType)) {
+                $parameters['type'] = $attributeType;
+            }
             $methods[] = [
                 'name' => $setterName,
-                'parameters' => [['name' => $propertyName]],
+                'parameters' => [$parameters],
                 'body' => "\$this->setData('{$attributeName}', \${$propertyName});" . PHP_EOL . "return \$this;",
                 'docblock' => [
                     'tags' => [
diff --git a/lib/internal/Magento/Framework/Api/Code/Generator/ExtensionAttributesInterfaceGenerator.php b/lib/internal/Magento/Framework/Api/Code/Generator/ExtensionAttributesInterfaceGenerator.php
index 3a658da307f88..937a0b5112780 100644
--- a/lib/internal/Magento/Framework/Api/Code/Generator/ExtensionAttributesInterfaceGenerator.php
+++ b/lib/internal/Magento/Framework/Api/Code/Generator/ExtensionAttributesInterfaceGenerator.php
@@ -21,6 +21,7 @@ class ExtensionAttributesInterfaceGenerator extends \Magento\Framework\Api\Code\
      * Initialize dependencies.
      *
      * @param \Magento\Framework\Api\ExtensionAttribute\Config $config
+     * @param \Magento\Framework\Reflection\TypeProcessor $typeProcessor
      * @param string|null $sourceClassName
      * @param string|null $resultClassName
      * @param Io $ioObject
@@ -29,6 +30,7 @@ class ExtensionAttributesInterfaceGenerator extends \Magento\Framework\Api\Code\
      */
     public function __construct(
         \Magento\Framework\Api\ExtensionAttribute\Config $config,
+        \Magento\Framework\Reflection\TypeProcessor $typeProcessor,
         $sourceClassName = null,
         $resultClassName = null,
         Io $ioObject = null,
@@ -40,6 +42,7 @@ public function __construct(
         }
         parent::__construct(
             $config,
+            $typeProcessor,
             $sourceClassName,
             $resultClassName,
             $ioObject,
diff --git a/lib/internal/Magento/Framework/Api/Test/Unit/Code/Generator/ExtensionAttributesGeneratorTest.php b/lib/internal/Magento/Framework/Api/Test/Unit/Code/Generator/ExtensionAttributesGeneratorTest.php
index bfdb3a0a2e8ac..bc7443488db72 100644
--- a/lib/internal/Magento/Framework/Api/Test/Unit/Code/Generator/ExtensionAttributesGeneratorTest.php
+++ b/lib/internal/Magento/Framework/Api/Test/Unit/Code/Generator/ExtensionAttributesGeneratorTest.php
@@ -15,6 +15,11 @@ class ExtensionAttributesGeneratorTest extends \PHPUnit_Framework_TestCase
      */
     protected $configMock;
 
+    /**
+     * @var \Magento\Framework\Reflection\TypeProcessor|\PHPUnit_Framework_MockObject_MockObject
+     */
+    protected $typeProcessorMock;
+
     /**
      * @var \Magento\Framework\Api\Code\Generator\ExtensionAttributesGenerator|\PHPUnit_Framework_MockObject_MockObject
      */
@@ -26,11 +31,17 @@ protected function setUp()
             ->disableOriginalConstructor()
             ->getMock();
 
+        $this->typeProcessorMock = $this->getMockBuilder('Magento\Framework\Reflection\TypeProcessor')
+            ->disableOriginalConstructor()
+            ->setMethods(null)
+            ->getMock();
+
         $objectManager = new \Magento\Framework\TestFramework\Unit\Helper\ObjectManager($this);
         $this->model = $objectManager->getObject(
             'Magento\Framework\Api\Code\Generator\ExtensionAttributesGenerator',
             [
                 'config' => $this->configMock,
+                'typeProcessor' => $this->typeProcessorMock,
                 'sourceClassName' => '\Magento\Catalog\Api\Data\Product',
                 'resultClassName' => '\Magento\Catalog\Api\Data\ProductExtension',
                 'classGenerator' => null
@@ -55,6 +66,11 @@ public function testGenerate()
                             Converter::DATA_TYPE => '\Magento\Bundle\Api\Data\OptionInterface[]',
                             Converter::RESOURCE_PERMISSIONS => [],
                         ],
+                        // Ensure type declaration is added to argument of setter
+                        'complex_object_attribute_with_type_declaration' => [
+                            Converter::DATA_TYPE => '\Magento\Bundle\Api\Data\BundleOptionInterface',
+                            Converter::RESOURCE_PERMISSIONS => [],
+                        ],
                     ],
                     'Magento\Catalog\Api\Data\Product' => [
                         'should_not_include' => [
diff --git a/lib/internal/Magento/Framework/Api/Test/Unit/Code/Generator/ExtensionAttributesInterfaceGeneratorTest.php b/lib/internal/Magento/Framework/Api/Test/Unit/Code/Generator/ExtensionAttributesInterfaceGeneratorTest.php
index e01121b13881c..2173304760615 100644
--- a/lib/internal/Magento/Framework/Api/Test/Unit/Code/Generator/ExtensionAttributesInterfaceGeneratorTest.php
+++ b/lib/internal/Magento/Framework/Api/Test/Unit/Code/Generator/ExtensionAttributesInterfaceGeneratorTest.php
@@ -29,6 +29,11 @@ public function testGenerate()
                             Converter::DATA_TYPE => '\Magento\Bundle\Api\Data\OptionInterface[]',
                             Converter::RESOURCE_PERMISSIONS => [],
                         ],
+                        // Ensure type declaration is added to argument of setter
+                        'complex_object_attribute_with_type_declaration' => [
+                            Converter::DATA_TYPE => '\Magento\Bundle\Api\Data\BundleOptionInterface',
+                            Converter::RESOURCE_PERMISSIONS => [],
+                        ],
                     ],
                     'Magento\Catalog\Api\Data\Product' => [
                         'should_not_include' => [
@@ -38,12 +43,17 @@ public function testGenerate()
                     ],
                 ]
             );
+        $typeProcessorMock = $this->getMockBuilder('Magento\Framework\Reflection\TypeProcessor')
+            ->disableOriginalConstructor()
+            ->setMethods(null)
+            ->getMock();
 
         /** @var \Magento\Framework\Api\Code\Generator\ExtensionAttributesInterfaceGenerator $model */
         $model = $objectManager->getObject(
             'Magento\Framework\Api\Code\Generator\ExtensionAttributesInterfaceGenerator',
             [
                 'config' => $configMock,
+                'typeProcessor' => $typeProcessorMock,
                 'sourceClassName' => '\Magento\Catalog\Api\Data\Product',
                 'resultClassName' => '\Magento\Catalog\Api\Data\ProductExtensionInterface',
                 'classGenerator' => null
diff --git a/lib/internal/Magento/Framework/Api/Test/Unit/Code/Generator/_files/SampleExtension.txt b/lib/internal/Magento/Framework/Api/Test/Unit/Code/Generator/_files/SampleExtension.txt
index 0f9838bd8736c..0078deb937e8b 100644
--- a/lib/internal/Magento/Framework/Api/Test/Unit/Code/Generator/_files/SampleExtension.txt
+++ b/lib/internal/Magento/Framework/Api/Test/Unit/Code/Generator/_files/SampleExtension.txt
@@ -40,4 +40,23 @@ class ProductExtension extends \Magento\Framework\Api\AbstractSimpleObject imple
         $this->setData('complex_object_attribute', $complexObjectAttribute);
         return $this;
     }
+
+    /**
+     * @return \Magento\Bundle\Api\Data\BundleOptionInterface|null
+     */
+    public function getComplexObjectAttributeWithTypeDeclaration()
+    {
+        return $this->_get('complex_object_attribute_with_type_declaration');
+    }
+
+    /**
+     * @param \Magento\Bundle\Api\Data\BundleOptionInterface
+     * $complexObjectAttributeWithTypeDeclaration
+     * @return $this
+     */
+    public function setComplexObjectAttributeWithTypeDeclaration(\Magento\Bundle\Api\Data\BundleOptionInterface $complexObjectAttributeWithTypeDeclaration)
+    {
+        $this->setData('complex_object_attribute_with_type_declaration', $complexObjectAttributeWithTypeDeclaration);
+        return $this;
+    }
 }
diff --git a/lib/internal/Magento/Framework/Api/Test/Unit/Code/Generator/_files/SampleExtensionInterface.txt b/lib/internal/Magento/Framework/Api/Test/Unit/Code/Generator/_files/SampleExtensionInterface.txt
index 75dde39b21519..4d5a7336a8076 100644
--- a/lib/internal/Magento/Framework/Api/Test/Unit/Code/Generator/_files/SampleExtensionInterface.txt
+++ b/lib/internal/Magento/Framework/Api/Test/Unit/Code/Generator/_files/SampleExtensionInterface.txt
@@ -26,4 +26,16 @@ interface ProductExtensionInterface extends \Magento\Framework\Api\ExtensionAttr
      * @return $this
      */
     public function setComplexObjectAttribute($complexObjectAttribute);
+
+    /**
+     * @return \Magento\Bundle\Api\Data\BundleOptionInterface|null
+     */
+    public function getComplexObjectAttributeWithTypeDeclaration();
+
+    /**
+     * @param \Magento\Bundle\Api\Data\BundleOptionInterface
+     * $complexObjectAttributeWithTypeDeclaration
+     * @return $this
+     */
+    public function setComplexObjectAttributeWithTypeDeclaration(\Magento\Bundle\Api\Data\BundleOptionInterface $complexObjectAttributeWithTypeDeclaration);
 }
diff --git a/lib/internal/Magento/Framework/Reflection/Test/Unit/TypeProcessorTest.php b/lib/internal/Magento/Framework/Reflection/Test/Unit/TypeProcessorTest.php
index 77b746e393297..6708b90525f52 100644
--- a/lib/internal/Magento/Framework/Reflection/Test/Unit/TypeProcessorTest.php
+++ b/lib/internal/Magento/Framework/Reflection/Test/Unit/TypeProcessorTest.php
@@ -115,6 +115,26 @@ public function testIsArrayType()
         $this->assertTrue($this->_typeProcessor->isArrayType('string[]'));
     }
 
+    public function testIsValidTypeDeclaration()
+    {
+        $this->assertTrue($this->_typeProcessor->isValidTypeDeclaration('Traversable')); // Interface
+        $this->assertTrue($this->_typeProcessor->isValidTypeDeclaration('stdObj')); // Class
+        $this->assertTrue($this->_typeProcessor->isValidTypeDeclaration('array'));
+        $this->assertTrue($this->_typeProcessor->isValidTypeDeclaration('callable'));
+        $this->assertTrue($this->_typeProcessor->isValidTypeDeclaration('self'));
+        $this->assertTrue($this->_typeProcessor->isValidTypeDeclaration('self'));
+        $this->assertFalse($this->_typeProcessor->isValidTypeDeclaration('string'));
+        $this->assertFalse($this->_typeProcessor->isValidTypeDeclaration('string[]'));
+        $this->assertFalse($this->_typeProcessor->isValidTypeDeclaration('int'));
+        $this->assertFalse($this->_typeProcessor->isValidTypeDeclaration('float'));
+        $this->assertFalse($this->_typeProcessor->isValidTypeDeclaration('double'));
+        $this->assertFalse($this->_typeProcessor->isValidTypeDeclaration('boolean'));
+        $this->assertFalse($this->_typeProcessor->isValidTypeDeclaration('[]'));
+        $this->assertFalse($this->_typeProcessor->isValidTypeDeclaration('mixed[]'));
+        $this->assertFalse($this->_typeProcessor->isValidTypeDeclaration('stdObj[]'));
+        $this->assertFalse($this->_typeProcessor->isValidTypeDeclaration('Traversable[]'));
+    }
+
     public function getArrayItemType()
     {
         $this->assertEquals('string', $this->_typeProcessor->getArrayItemType('str[]'));
diff --git a/lib/internal/Magento/Framework/Reflection/TypeProcessor.php b/lib/internal/Magento/Framework/Reflection/TypeProcessor.php
index a9646443de11e..6dcbe7d992659 100644
--- a/lib/internal/Magento/Framework/Reflection/TypeProcessor.php
+++ b/lib/internal/Magento/Framework/Reflection/TypeProcessor.php
@@ -14,6 +14,7 @@
  * Type processor of config reader properties
  *
  * @SuppressWarnings(PHPMD.CouplingBetweenObjects)
+ * @SuppressWarnings(PHPMD.ExcessiveClassComplexity)
  */
 class TypeProcessor
 {
@@ -419,6 +420,18 @@ public function isArrayType($type)
         return (bool)preg_match('/(\[\]$|^ArrayOf)/', $type);
     }
 
+    /**
+     * Check if given type is valid to use as an argument type declaration
+     *
+     * @see http://php.net/manual/en/functions.arguments.php#functions.arguments.type-declaration
+     * @param string $type
+     * @return bool
+     */
+    public function isValidTypeDeclaration($type)
+    {
+        return !($this->isTypeSimple($type) || $this->isTypeAny($type) || $this->isArrayType($type));
+    }
+
     /**
      * Get item type of the array.
      *