diff --git a/reference/constraints/All.rst b/reference/constraints/All.rst
index cef70cc3690..0a95103d62e 100644
--- a/reference/constraints/All.rst
+++ b/reference/constraints/All.rst
@@ -39,7 +39,7 @@ entry in that array:
              *     @Assert\Length(min=5)
              * })
              */
-             protected $favoriteColors = [];
+            protected $favoriteColors = [];
         }
 
     .. code-block:: yaml
diff --git a/reference/constraints/Bic.rst b/reference/constraints/Bic.rst
index 41c43e82359..7995431e7d8 100644
--- a/reference/constraints/Bic.rst
+++ b/reference/constraints/Bic.rst
@@ -73,8 +73,6 @@ will contain a Business Identifier Code (BIC).
 
         class Transaction
         {
-            protected $businessIdentifierCode;
-
             public static function loadValidatorMetadata(ClassMetadata $metadata)
             {
                 $metadata->addPropertyConstraint('businessIdentifierCode', new Assert\Bic());
diff --git a/reference/constraints/Callback.rst b/reference/constraints/Callback.rst
index 2905733cc79..95ab8a6a2ac 100644
--- a/reference/constraints/Callback.rst
+++ b/reference/constraints/Callback.rst
@@ -87,6 +87,11 @@ Configuration
             {
                 $metadata->addConstraint(new Assert\Callback('validate'));
             }
+
+            public function validate(ExecutionContextInterface $context, $payload)
+            {
+                // ...
+            }
         }
 
 The Callback Method
diff --git a/reference/constraints/CardScheme.rst b/reference/constraints/CardScheme.rst
index 52e2b72569e..1a68b413865 100644
--- a/reference/constraints/CardScheme.rst
+++ b/reference/constraints/CardScheme.rst
@@ -84,8 +84,6 @@ on an object that will contain a credit card number.
 
         class Transaction
         {
-            protected $cardNumber;
-
             public static function loadValidatorMetadata(ClassMetadata $metadata)
             {
                 $metadata->addPropertyConstraint('cardNumber', new Assert\CardScheme([
diff --git a/reference/constraints/Choice.rst b/reference/constraints/Choice.rst
index 302faca7255..231f2acba8f 100644
--- a/reference/constraints/Choice.rst
+++ b/reference/constraints/Choice.rst
@@ -112,8 +112,6 @@ If your valid choice list is simple, you can pass them in directly via the
 
         class Author
         {
-            protected $genre;
-
             public static function loadValidatorMetadata(ClassMetadata $metadata)
             {
                 $metadata->addPropertyConstraint(
diff --git a/reference/constraints/Collection.rst b/reference/constraints/Collection.rst
index 7e23a4cf8ed..94db7909dea 100644
--- a/reference/constraints/Collection.rst
+++ b/reference/constraints/Collection.rst
@@ -141,8 +141,6 @@ following:
 
         class Author
         {
-            private $options = [];
-
             public static function loadValidatorMetadata(ClassMetadata $metadata)
             {
                 $metadata->addPropertyConstraint('profileData', new Assert\Collection([
@@ -208,7 +206,7 @@ you can do the following:
              *     }
              * )
              */
-             protected $profileData = ['personal_email'];
+            protected $profileData = ['personal_email'];
         }
 
     .. code-block:: yaml
@@ -272,9 +270,10 @@ you can do the following:
             {
                 $metadata->addPropertyConstraint('profileData', new Assert\Collection([
                     'fields' => [
-                        'personal_email'  => new Assert\Required(
-                            [new Assert\NotBlank(), new Assert\Email()]
-                        ),
+                        'personal_email'  => new Assert\Required([
+                            new Assert\NotBlank(),
+                            new Assert\Email(),
+                        ]),
                         'alternate_email' => new Assert\Optional(new Assert\Email()),
                     ],
                 ]));
diff --git a/reference/constraints/Count.rst b/reference/constraints/Count.rst
index b37797dafc6..6308aeba33a 100644
--- a/reference/constraints/Count.rst
+++ b/reference/constraints/Count.rst
@@ -45,7 +45,7 @@ you might add the following:
              *      maxMessage = "You cannot specify more than {{ limit }} emails"
              * )
              */
-             protected $emails = [];
+            protected $emails = [];
         }
 
     .. code-block:: yaml
@@ -93,8 +93,8 @@ you might add the following:
             public static function loadValidatorMetadata(ClassMetadata $metadata)
             {
                 $metadata->addPropertyConstraint('emails', new Assert\Count([
-                    'min'        => 1,
-                    'max'        => 5,
+                    'min' => 1,
+                    'max' => 5,
                     'minMessage' => 'You must specify at least one email',
                     'maxMessage' => 'You cannot specify more than {{ limit }} emails',
                 ]));
diff --git a/reference/constraints/Country.rst b/reference/constraints/Country.rst
index 2ef348f4b12..7c52723953a 100644
--- a/reference/constraints/Country.rst
+++ b/reference/constraints/Country.rst
@@ -32,7 +32,7 @@ Basic Usage
             /**
              * @Assert\Country
              */
-             protected $country;
+            protected $country;
         }
 
     .. code-block:: yaml
diff --git a/reference/constraints/Date.rst b/reference/constraints/Date.rst
index 46cad1e1a73..b9816764cea 100644
--- a/reference/constraints/Date.rst
+++ b/reference/constraints/Date.rst
@@ -34,7 +34,7 @@ Basic Usage
             /**
              * @Assert\Date
              */
-             protected $birthday;
+            protected $birthday;
         }
 
     .. code-block:: yaml
diff --git a/reference/constraints/DateTime.rst b/reference/constraints/DateTime.rst
index b670bb71629..c81c04f8626 100644
--- a/reference/constraints/DateTime.rst
+++ b/reference/constraints/DateTime.rst
@@ -35,7 +35,7 @@ Basic Usage
             /**
              * @Assert\DateTime
              */
-             protected $createdAt;
+            protected $createdAt;
         }
 
     .. code-block:: yaml
diff --git a/reference/constraints/Email.rst b/reference/constraints/Email.rst
index c07cb4845d1..e196150bb52 100644
--- a/reference/constraints/Email.rst
+++ b/reference/constraints/Email.rst
@@ -39,7 +39,7 @@ Basic Usage
              *     checkMX = true
              * )
              */
-             protected $email;
+            protected $email;
         }
 
     .. code-block:: yaml
diff --git a/reference/constraints/Image.rst b/reference/constraints/Image.rst
index b907ca56d50..4f5529186dd 100644
--- a/reference/constraints/Image.rst
+++ b/reference/constraints/Image.rst
@@ -211,13 +211,11 @@ following code:
 
         class Author
         {
-            // ...
-
             public static function loadValidatorMetadata(ClassMetadata $metadata)
             {
                 $metadata->addPropertyConstraint('headshot', new Assert\Image([
-                    'allowLandscape'    => false,
-                    'allowPortrait'     => false,
+                    'allowLandscape' => false,
+                    'allowPortrait' => false,
                 ]));
             }
         }
diff --git a/reference/constraints/Ip.rst b/reference/constraints/Ip.rst
index 7adfce8c2ff..c16a94d6df3 100644
--- a/reference/constraints/Ip.rst
+++ b/reference/constraints/Ip.rst
@@ -35,7 +35,7 @@ Basic Usage
             /**
              * @Assert\Ip
              */
-             protected $ipAddress;
+            protected $ipAddress;
         }
 
     .. code-block:: yaml
diff --git a/reference/constraints/IsFalse.rst b/reference/constraints/IsFalse.rst
index 4fb67e1c63d..10148287e9d 100644
--- a/reference/constraints/IsFalse.rst
+++ b/reference/constraints/IsFalse.rst
@@ -55,10 +55,10 @@ method returns **false**:
              *     message = "You've entered an invalid state."
              * )
              */
-             public function isStateInvalid()
-             {
+            public function isStateInvalid()
+            {
                 // ...
-             }
+            }
         }
 
     .. code-block:: yaml
@@ -99,10 +99,17 @@ method returns **false**:
         {
             public static function loadValidatorMetadata(ClassMetadata $metadata)
             {
-                $metadata->addGetterConstraint('stateInvalid', new Assert\IsFalse());
+                $metadata->addGetterConstraint('stateInvalid', new Assert\IsFalse([
+                    'message' => 'You've entered an invalid state.',
+                ]));
             }
         }
 
+        public function isStateInvalid()
+        {
+            // ...
+        }
+
 Options
 -------
 
diff --git a/reference/constraints/IsTrue.rst b/reference/constraints/IsTrue.rst
index ca5d0c7d534..6ea7f30037d 100644
--- a/reference/constraints/IsTrue.rst
+++ b/reference/constraints/IsTrue.rst
@@ -56,7 +56,7 @@ Then you can constrain this method with ``IsTrue``.
             protected $token;
 
             /**
-             * @Assert\IsTrue(message="The token is invalid")
+             * @Assert\IsTrue(message="The token is invalid.")
              */
             public function isTokenValid()
             {
@@ -100,8 +100,6 @@ Then you can constrain this method with ``IsTrue``.
 
         class Author
         {
-            protected $token;
-
             public static function loadValidatorMetadata(ClassMetadata $metadata)
             {
                 $metadata->addGetterConstraint('tokenValid', new IsTrue([
diff --git a/reference/constraints/Isbn.rst b/reference/constraints/Isbn.rst
index b905d92cf06..4c543496084 100644
--- a/reference/constraints/Isbn.rst
+++ b/reference/constraints/Isbn.rst
@@ -84,12 +84,10 @@ on an object that will contain an ISBN.
 
         class Book
         {
-            protected $isbn;
-
             public static function loadValidatorMetadata(ClassMetadata $metadata)
             {
                 $metadata->addPropertyConstraint('isbn', new Assert\Isbn([
-                    'type'    => 'isbn10',
+                    'type' => 'isbn10',
                     'message' => 'This value is not valid.',
                 ]));
             }
diff --git a/reference/constraints/Issn.rst b/reference/constraints/Issn.rst
index 372fbc4b0f8..f409a17b94e 100644
--- a/reference/constraints/Issn.rst
+++ b/reference/constraints/Issn.rst
@@ -35,7 +35,7 @@ Basic Usage
             /**
              * @Assert\Issn
              */
-             protected $issn;
+            protected $issn;
         }
 
     .. code-block:: yaml
@@ -87,7 +87,7 @@ Options
 message
 ~~~~~~~
 
-**type**: ``String`` default: ``This value is not a valid ISSN.``
+**type**: ``string`` default: ``This value is not a valid ISSN.``
 
 The message shown if the given value is not a valid ISSN.
 
diff --git a/reference/constraints/Language.rst b/reference/constraints/Language.rst
index fa83769328f..29eace137db 100644
--- a/reference/constraints/Language.rst
+++ b/reference/constraints/Language.rst
@@ -33,7 +33,7 @@ Basic Usage
             /**
              * @Assert\Language
              */
-             protected $preferredLanguage;
+            protected $preferredLanguage;
         }
 
     .. code-block:: yaml
diff --git a/reference/constraints/Length.rst b/reference/constraints/Length.rst
index 39d91eb560a..c2f2b7ab030 100644
--- a/reference/constraints/Length.rst
+++ b/reference/constraints/Length.rst
@@ -52,7 +52,7 @@ and "50", you might add the following:
              *      maxMessage = "Your first name cannot be longer than {{ limit }} characters"
              * )
              */
-             protected $firstName;
+            protected $firstName;
         }
 
     .. code-block:: yaml
@@ -104,8 +104,8 @@ and "50", you might add the following:
             public static function loadValidatorMetadata(ClassMetadata $metadata)
             {
                 $metadata->addPropertyConstraint('firstName', new Assert\Length([
-                    'min'        => 2,
-                    'max'        => 50,
+                    'min' => 2,
+                    'max' => 50,
                     'minMessage' => 'Your first name must be at least {{ limit }} characters long',
                     'maxMessage' => 'Your first name cannot be longer than {{ limit }} characters',
                 ]));
diff --git a/reference/constraints/Locale.rst b/reference/constraints/Locale.rst
index eb8b1bd0651..932bae1b5a3 100644
--- a/reference/constraints/Locale.rst
+++ b/reference/constraints/Locale.rst
@@ -37,7 +37,7 @@ Basic Usage
             /**
              * @Assert\Locale
              */
-             protected $locale;
+            protected $locale;
         }
 
     .. code-block:: yaml
diff --git a/reference/constraints/Range.rst b/reference/constraints/Range.rst
index f69ec3231ba..cfb4e166d55 100644
--- a/reference/constraints/Range.rst
+++ b/reference/constraints/Range.rst
@@ -92,8 +92,8 @@ you might add the following:
             public static function loadValidatorMetadata(ClassMetadata $metadata)
             {
                 $metadata->addPropertyConstraint('height', new Assert\Range([
-                    'min'        => 120,
-                    'max'        => 180,
+                    'min' => 120,
+                    'max' => 180,
                     'minMessage' => 'You must be at least {{ limit }}cm tall to enter',
                     'maxMessage' => 'You cannot be taller than {{ limit }}cm to enter',
                 ]));
diff --git a/reference/constraints/Regex.rst b/reference/constraints/Regex.rst
index e1567d7baff..830684cd030 100644
--- a/reference/constraints/Regex.rst
+++ b/reference/constraints/Regex.rst
@@ -156,7 +156,7 @@ it a custom message:
             {
                 $metadata->addPropertyConstraint('firstName', new Assert\Regex([
                     'pattern' => '/\d/',
-                    'match'   => false,
+                    'match' => false,
                     'message' => 'Your name cannot contain a number',
                 ]));
             }
@@ -257,7 +257,7 @@ need to specify the HTML5 compatible pattern in the ``htmlPattern`` option:
             public static function loadValidatorMetadata(ClassMetadata $metadata)
             {
                 $metadata->addPropertyConstraint('name', new Assert\Regex([
-                    'pattern'     => '/^[a-z]+$/i',
+                    'pattern' => '/^[a-z]+$/i',
                     'htmlPattern' => '^[a-zA-Z]+$',
                 ]));
             }
diff --git a/reference/constraints/Time.rst b/reference/constraints/Time.rst
index 2051f1e4d02..7a57cc1b507 100644
--- a/reference/constraints/Time.rst
+++ b/reference/constraints/Time.rst
@@ -37,7 +37,7 @@ of the day when the event starts:
             /**
              * @Assert\Time
              */
-             protected $startsAt;
+            protected $startsAt;
         }
 
     .. code-block:: yaml
diff --git a/reference/constraints/Type.rst b/reference/constraints/Type.rst
index a9e26e2f531..08a8f5e7471 100644
--- a/reference/constraints/Type.rst
+++ b/reference/constraints/Type.rst
@@ -100,7 +100,7 @@ This will check if ``firstName`` is of type ``string`` and that ``age`` is an
                 $metadata->addPropertyConstraint('firstName', new Assert\Type('string'));
 
                 $metadata->addPropertyConstraint('age', new Assert\Type([
-                    'type'    => 'integer',
+                    'type' => 'integer',
                     'message' => 'The value {{ value }} is not a valid {{ type }}.',
                 ]));
             }
diff --git a/reference/constraints/UniqueEntity.rst b/reference/constraints/UniqueEntity.rst
index e773e3313d7..15cfe251407 100644
--- a/reference/constraints/UniqueEntity.rst
+++ b/reference/constraints/UniqueEntity.rst
@@ -51,14 +51,10 @@ your user table:
         class Author
         {
             /**
-             * @var string $email
-             *
              * @ORM\Column(name="email", type="string", length=255, unique=true)
              * @Assert\Email
              */
             protected $email;
-
-            // ...
         }
 
     .. code-block:: yaml
@@ -104,7 +100,7 @@ your user table:
             public static function loadValidatorMetadata(ClassMetadata $metadata)
             {
                 $metadata->addConstraint(new UniqueEntity([
-                    'fields'  => 'email',
+                    'fields' => 'email',
                 ]));
 
                 $metadata->addPropertyConstraint('email', new Assert\Email());
@@ -285,9 +281,9 @@ Consider this example:
             public static function loadValidatorMetadata(ClassMetadata $metadata)
             {
                 $metadata->addConstraint(new UniqueEntity([
-                    'fields'    => ['host', 'port'],
+                    'fields' => ['host', 'port'],
                     'errorPath' => 'port',
-                    'message'   => 'This port is already in use on that host.',
+                    'message' => 'This port is already in use on that host.',
                 ]));
             }
         }
diff --git a/reference/constraints/Url.rst b/reference/constraints/Url.rst
index 08583b1196d..9e8e48a1aa9 100644
--- a/reference/constraints/Url.rst
+++ b/reference/constraints/Url.rst
@@ -35,7 +35,7 @@ Basic Usage
             /**
              * @Assert\Url
              */
-             protected $bioUrl;
+            protected $bioUrl;
         }
 
     .. code-block:: yaml
@@ -115,7 +115,7 @@ You can use the following parameters in this message:
              *    message = "The url '{{ value }}' is not a valid url",
              * )
              */
-             protected $bioUrl;
+            protected $bioUrl;
         }
 
     .. code-block:: yaml
@@ -187,7 +187,7 @@ the ``ftp://`` type URLs to be valid, redefine the ``protocols`` array, listing
              *    protocols = {"http", "https", "ftp"}
              * )
              */
-             protected $bioUrl;
+            protected $bioUrl;
         }
 
     .. code-block:: yaml
@@ -265,7 +265,7 @@ option to the value of any of the ``CHECK_DNS_TYPE_*`` constants in the
              *    checkDNS = "ANY"
              * )
              */
-             protected $bioUrl;
+            protected $bioUrl;
         }
 
     .. code-block:: yaml
@@ -338,7 +338,7 @@ DNS check failed.
              *    dnsMessage = "The host '{{ value }}' could not be resolved."
              * )
              */
-             protected $bioUrl;
+            protected $bioUrl;
         }
 
     .. code-block:: yaml
diff --git a/reference/constraints/UserPassword.rst b/reference/constraints/UserPassword.rst
index 27dc8874c45..dd853e779ab 100644
--- a/reference/constraints/UserPassword.rst
+++ b/reference/constraints/UserPassword.rst
@@ -46,7 +46,7 @@ the user's current password:
              *     message = "Wrong value for your current password"
              * )
              */
-             protected $oldPassword;
+            protected $oldPassword;
         }
 
     .. code-block:: yaml
diff --git a/reference/constraints/Uuid.rst b/reference/constraints/Uuid.rst
index 0ca5a5fca33..f89ed1e271c 100644
--- a/reference/constraints/Uuid.rst
+++ b/reference/constraints/Uuid.rst
@@ -37,7 +37,7 @@ Basic Usage
             /**
              * @Assert\Uuid
              */
-             protected $identifier;
+            protected $identifier;
         }
 
     .. code-block:: yaml
diff --git a/reference/constraints/Valid.rst b/reference/constraints/Valid.rst
index 1cfa3d21865..97dc22c093d 100644
--- a/reference/constraints/Valid.rst
+++ b/reference/constraints/Valid.rst
@@ -153,9 +153,6 @@ stores an ``Address`` instance in the ``$address`` property::
 
         class Address
         {
-            protected $street;
-            protected $zipCode;
-
             public static function loadValidatorMetadata(ClassMetadata $metadata)
             {
                 $metadata->addPropertyConstraint('street', new Assert\NotBlank());
@@ -172,10 +169,6 @@ stores an ``Address`` instance in the ``$address`` property::
 
         class Author
         {
-            protected $firstName;
-            protected $lastName;
-            protected $address;
-
             public static function loadValidatorMetadata(ClassMetadata $metadata)
             {
                 $metadata->addPropertyConstraint('firstName', new Assert\NotBlank());
@@ -238,8 +231,6 @@ an invalid address. To prevent that, add the ``Valid`` constraint to the
 
         class Author
         {
-            protected $address;
-
             public static function loadValidatorMetadata(ClassMetadata $metadata)
             {
                 $metadata->addPropertyConstraint('address', new Assert\Valid());